I agree it was uncalled for. Sounds like he has issues but I wouldn't assume they were with you. Probably triggered by the title of the book you chose. And he has probably only heard the bad tales from his relatives and not about the normal people that have mental health issues. The news media doesn't help us out either. Hopefully, that's all it was. Let it go unless he shows other signs of having a particular problem with you.
Gayle