Is it abnormal if my 10 year old son wants to sleep in the same bed as me?

the opinion of others does at times serve as a neccesary litmus test. I think this is one of them.

The fact that this child does not live with mom is even more reason to me to avoid this sort of coddling. The boy needs to be given the message that mom is still mom regardless of who has custody and that each parent is equal. This is her responsibility to ensure this is so. Mom needs to parent just as she would should he live with her permamently. At every effort should a noncustodial parent avoid the time they spend with their child turning into a holiday rather than a visit. This is why it's important to establish a healthy routine. It is the parent's responsibility to do so. The non-custodial home should be another home and NOT a vacation destination.

Separation happened years when op lost custody. If he still lives out of state with his dad, how frequent are these visits. Is him sleeping in bed is the only concern?

What does your heart tell you is right? What do your deepest, most honest mothering instincts tell you to do?

Trust your instincts. Have you asked him why he comes to you? Does he get scared and if so, of what? Nightmares? Does he know why he does it? That might be worth exploring.

Well, when he visits his aunt, she takes him to all these theme parks in Florida.

Nightmares can be utterly terrifying. Poor guy. Has be been able to tell you what they are about?

Aunt isn't a non custodial patent. There is nothing wrong in taking kids places. You can do that. I think the point was that you want him to have normal home life when he is with you. It is understandable he wants to sleep with you if he has nightmares. How often does he visit?