My intuition tells me, something doesn't feel right.

I don’t know what it is but my intuition is telling me that something isn’t right, something feels very wrong.
I asked my bf to use his cell phone, I find out he has a lock to his phone and to his contact list. He was driving his car at the time, so I asked him to give me his password so that I can call my sister.

He snaps at me and tells me that he’ll unlock his phone later. I asked him again and said that its okay because I can do it for him. Things just got very quite in the car.

I asked him what is it that he’s hiding from me? Why can’t he trust me with his password? Who is in his contact list that he doesn’t want me to find out about?
Am I thinking too much?

You *could* be thinking too much but I have a lock on my phone for no REAL reason other than its mine and I want to have a lock.
Or you have reason to be suspicious..

This is a tough one because I can understand why it would set off little alarms in your head. Some people really are super protective of their phone and the things on it that they consider personal. I have been married for 14 years and my husband is private with the information on his phone, he feels it is his phone so it is none of my business what may be on it. I on the other hand am very open with who I am texting or calling.

Maybe it is worth trying to talk to your boyfriend about this, maybe try explaining that it just kind of caught you off guard and that you wouldn't want to snoop through his phone. Perhaps he has a reasonable reason to keep the information private.

Personally I don't think your warning flags going off are not unjustified in my opinion. It sounds as if this is new behavior from your bf. I'm assuming by the way it surprised you that he hasn't done this before and if that's the case, it is something to be suspicious about. What, if he has locked his cell phone for fear of other people getting access to it other than you, frankly, he would have been up front about it. At least if it were me and the reason was justified, I would have done everything to ease your mind with the explanation at least but he snapped at you which is a bad sign. Secondly he didn't offer to let you unlock it for him, which, it also sounds as though you would normally expect him to give into. So if it's not some other reason for locking his phone, it does sound like it could be hiding something from you IMO. Of course this is just my opinion on this so.. At least though it is something that you need to look into further. I would go with your intuition on this and talk to him. Depending on how he reacts to your asking why he locked it and why he won't let you just enter the password, I would judge from that. For me personally, the one I am closest to, my SO, should have nothing hidden from her. But that's just me. Again, if this is not new behavior but something you didn't know about him it might be ok, but if it's new behavior that's changed, you just might have something to worry about. I'm sorry but that's just my take.

Is he on the same family plan with you or does he have a separate plan? If he is on the same plan, you can look up his call records online. It would be just numbers without names, but still, you can see trends. If he has his own plan... I do not know, I think if I were someone who tried to conceal his call records, I would use codenames instead of real names in contacts and I would delete each call from the log instantly. I do not think that using a lock is the most effective way to be discreet about one's calling.

I would be suspicious. I had a bad feeling about my live in BF's phone and email, so I actually hacked into his email (I know it was wrong). What I found in there blew my mind. He had advertised in CL for pay for sex and had responses from women wanting $$ for sex. He's a truck driver. Plus, I kind of thought he was involved with a woman he calls his "neice", and now I know he is. She's a sex phone operator. She won't sleep with him, but sends him racy pics, etc. This had been a problem before I saw the emails, but I think it has all put the final nail in the coffin.

This could be a sign he's either hiding something or very secretive. Personally I keep everything open and have nothing to hide, I'm an open book but that's just me. I don't think it's very healthy for a relationship when people are being sneaky and hiding things

Completely agree. When you have to hide something from the person you're supposed to have the strongest and most secure relationshp with it's a big red flag.