I would not let it bother you and I hope it did/does not bother your gf.

Infact, I would have had some fun with it as it reminds me of a scene from the movie Ferris Bueller's Day Off.

In the scene Ferris calls to the school pretending to be his girl friend's father and he needs his "daughter" pulled from school because of a death in the family.

Up drives Ferris in a convertible pretending to be Sloane's (the gf) father. He is wearing a trench coat a hat and sun glasses. The principal is at the top of the stairs. Sloane walks down the steps into the car and then [this is where you could have had some fun with the flight attendant], "her father" and her start kissing.

OMG, I'm LMAO here typing this out. It would have been priceless to have seen the flight attendants expression!

The biggest age difference between me and my gf was 21 years. I was in university and she worked for AC in the MLL (T-2, behind domestic check-in, beside the chapel, when the MLL was pre-security). And besides...my wife is 11 years older than me and when I was younger it was funny to see how we were addressed.

One thing is for sure -- it's not worth worrying what others think / say -- it's none of their business as long as you're having fun...err..I mean as long as you're happy

Cheers