I don't know how he's doing this *tmi maybe

So my 5 month old sleeps through the night but also doesn't pee in his diaper like it's just dry when I go to change him. He pees any other time just not when he's asleep. He has been doing this for 6 weeks now. I'm surprised and excited honestly because if he keeps this up then he should be easy to potty train when he gets that age. My question is though Should I be concerned about it? With his bladder being small I would think he wouldn't be able to hold it. what do you think? anybody else go through something like this?