"Hey, I just wanted to introduce myself because Facebook thinks we may know each other but even though that's most likely not the case, I wouldn't mind making more friends that are musicians! You're an amazing guitarist and singer!"
He seemed really cool so I wanted to take the risk and send a message, tho it seems like he isn't on Facebook often and I sent this a week ago, the last thing he updated was in February so I can see. I'm not sure if guys wouldn't mind someone sending a message or how a guy would react cause we don't know each other at all, but would this be seen as weird?