Is my bf flirting ?

Hey guys so today I was just going through my bf’s tik tok and I saw that this girl had commented on one of his videos so I went to her page and I saw that the girl had posted a video with her dog, when I went into the comment section, I saw that my bf has commented “ your dog is cuteerrr thank you “ as a joke. I checked my bf’s insta and they aren’t following each other on insta tho .., however, is my bf flirting with her ? Or just joking and nothing serious ? And should I confront my bf and let him know I’ve found out about the comment ? ( psa: my bf and I are involved in each other lives and we have met each other families and friends and everything and we have been dating for 4 months) I should add that he does like pics on insta but never comments on girls posts on insta or anywhere usually