Baby sleeps through the night.... all the time?

I have an 8mo who has never formally been sleep trained. We did all the things like putting him down drowsy but awake, separating feeding from sleeping, giving him some space to fall asleep independently (but never CIO). He's been pretty good, generally speaking. He started mostly sleeping through the night around 3 months, until the 4 month sleep regression hit us hard from 4.5 months- 6 months. Since then, he's back to sleeping through the night.... for the most part. Usually no more than 1 or 2 nights per week, he will wake up in the middle of the night for no apparent reason. Lately, he has been inconsolable and is up for an hour or so with truly only the passage of time being what gets him to fall back asleep. I don't think it is sleep related because he has done it on days when he naps 2.5 hours or days when he naps 3.5 hours. I don't think its food related because if it was, he'd only go back down if he ate. We do end up feeding him sometimes, but it is a very small amount (2 ounces), and doesn't seem to accelerate the amount of time it takes him to go back to sleep. I've also tried letting him BF in the middle of the night and that also doesn't make a difference.

My question is - is this normal? Is it just expected that even if your baby sleeps through the night for the most part, there will be wake ups for no apparent reason from time to time? I do think there have also been stretches of a week or two with no wakings but it is all such a blur I can't be sure.