Thirty-one year old kid working as school janitor

Last week I got my free flu shot, in the cafeteria of the high school I used to work at (I now just work at an elementary school).  I went around back, and luckily ran into a former co-worker who was dumping garbages.  It was cool to get to see him, and I was able to just go directly inside along with him, instead of going through the front, going to main office, checking in, getting visitor name tag, etc. etc.  I chatted with him for a minute, then followed others down to the cafeteria to get the shot.  A lady was there to organize us and hand out the forms we need to fill out.  She looked at me kinda sideways and said, “How old are you?”
“Me?  I’m thirty-one.”
“Oh, I thought you were a kid!”
“Oh, yeah, I get that sometimes.”
“OK good… well you’re lucky.”

I think she meant lucky that I look so young?  I do feel lucky – I like passing as a kid.   And I was even wearing my janitor uniform including ID badge on this occasion and everything, ’cause I was heading straight to work.  Don’t know of many high-schoolers who’d be sporting that outfit.