Hi J, welcome back.
I'm not familiar with your story, although I've been a member of this community almost as long as you.
"Call me." seems pretty dramatic and imperious to me. Is this guy the sort to want to stir the stink?
"Call me, please, I'd like to speak with you about ___" would be more likely to get me to pick up the phone. But that's me.
Call him, don't call him; whichever you prefer. Or you could FB message him and ask him why he wants to talk to you. But it's nothing to get too worked up over.