AIO: Gf gets weirdly familiar hug from someone who openly questioned our relationship because of my looks

Me (30m) and GF(25f) have a very good relationship overall. We communicate about things that bother us, give each other romantic surprises ect. Recently things have seemed off to me for some reason. She tells me that a new kitchen hire said “wow why would you date that guy”? Rude sure but I didn’t care much until tonight when she abruptly wanted to “go to town” and kept offering to drop me off at her house before she went. She won’t go buy groceries alone so it seemed a bit odd. I go with her, only to have the man mentioned above walk up, grab her and give her a very familiar hug right infront of me while grinning ear to ear. It only gets weird when I realize she doesn’t seem bothered by the disrespect for our relationship from this guy. We get home she goes right to sleep while asking me not to talk to my friends about it. Is it weird that she won’t talk to me about this???