Well I wasn't there, but from what I've read, despite the fact that your grandpa is old school, he indeed is accepting you (in his way) and bending backward not to step on your toes.
He did not preach, did not ignore your bf, did not say anything offensive about you, but tried to get a feel of your bf. in the old school ways, acknowledging him and taking an interest of him is very polite. I think your bf recognized this as such too.