I have had the opposite conversation with a guy at work.

"Hey dude, you bipolar or something?"

"Yup"

"Holy ****, I'm sorry, I hope I didn't offend you"

*Laughing* "No, but now you know"

He has actually now become one of my accountability partners, he will let me know when I am off, and if I say something out of the way to him, he doesn't take it other than I'm more upset at myself for not keeping track of my moods.