Quoting justanothamotha:" They can fear falling, not being able to find you, etc. They have natural built in fears. They don't ... [snip!] ... can make them worse - but they aren't the cause of them. Plenty of stressed out over tired kids never have a night terror."
That makes more sense. I just couldn't figure out what would stress him out or make him fear something when during the day he's fine. He does cry or whine when we walk out of them room when he's in his crib for a bit. So he does miss us or fear not seeing us. Thank you!