Front seat baby - What do you do?

I work fast food, so I see tons of different people every day. Today, a lady came through the drive thru to collect her order, and I noticed in the passenger seat next to her, a (somewhere around the age) 6 month old little boy. Old enough to hold himself up, but not to walk/talk, etc. He was sitting in the front seat, no car seat, seat belt, nothing. She had to have seen me looking, cuz she glared at me the whole time.

My question, is that something I should go to the police about? She had out of state plates, so I thought maybe it'd be harder to find. But it definitely didn't feel right just letting her leave with that little one so vulnerable.