I always wondered this myself.
I know that if you pump/express milk and do not refridgerate, it's good at room temp for 8 hours, but who has extra milk at the end of the night?
Well, one way to find out! Maybe it will smell sour if it goes bad? If not, he'll get a tummyache, I guess.
Sorry I can't be of more help. If you find out, tell me. I would love to know for the next one! I'll tell you if I run into anything.