I feel so bad I slept in and my baby didn’t cry

Usually my 15 month old cries or lets me know he’s awake somehow but he didn’t today, and hasn’t done it for a few times now. I have slept in for some reason and idk if he is sleeping In too or just hanging out in his crib for a few hours! That’s not ok right? Yeesh im freaking out about this I’m gonna start using a baby monitor again.

I don’t like the idea of him just being alone for 3 hours in his crib while I sleep!!! My room is right across from his and I usually wake up from the slightest noises.

Am I overreacting?