Has something like this happened to anyone else?

OK my girlfriend is a year older than me she's 21 and im 20 BUT no one would ever know if I didn't tell them.

She looks younger than she is by a few years without trying and if she really tries she can sorta pass off as 12

I have always looked way older than I am. Back in high school I was actually mistaken by students as a teacher a few times. And when I was 15 I grew my beard out and was actually once mistaken for my own parent

None of this ever really bothered me until a while back When we went to walmart. She likes it when I let her ride in the cart and I push her. I usually don't mind she's easy to push and we rarely get enough to where there's not enough room for her and the items. But this one time we were there and we passed this man who was shopping with his little girl riding in the cart we exchanged pleasantries and he said something to the effect of I guess we're both out here doing the same. I didn't think much of it and moved on, it didn't occur to me until later but he thought that I was my girlfriends father. I asked my girl about it and she thought it was funny but I was actually a bit disturbed by it.

Anyways has anyone else ever had anything similar happen to them?