I'm an adult w/ kids damnit!

So my husband had a work picnic today and I decided why not make it my girls first outing. I had a lot of fun and met some other twin moms. well I stood up to take care of my fussing babies as my husband was getting us food. well another mom sat down and started talking to the moms I was talking to and ask if the babies in the stroller was one of theirs. I was clearly attending to MY kids. I stood up and they said no they're her's. she looked a little confused and said "aren't you a little young?" the chick was 18. like what the heck?! did she think I was 16 or something?! I wanted to say something, but I wasn't about to open that can of worms. I just waved and went back to my kids. edit: Yeah I'm just a little tired of being called or treated like a kid. she wasn't the first to do it. I realize now I might've overreacted, but agian I just want to be treated like an adult.