I just feel it's strange that he stayed dry all through the night without waking for around 4 weeks after day training. Then started waking for a wee.
I think a lot of LOs do this, enough to make it well within the range of "normal".
If something else is waking him (such as changes in sleep needs or developmental stuff) he is likely to need to wee because he has woken, his body just kicks in the "awake" mode and the hormone to not wee turns off and he then needs a wee. It's not necessarily the need to wee that is waking him but something else.
If he goes back to sleep but isn't going into a good deep sleep he could wake again and it's the same, because he's awake he could need to wee even if it hasn't been that long.
Some of it could also be:
- he knows he can get your attention by calling out need to wee (especially if he's relatively recently PT, you've been responding rapidly to him saying he needs to wee so he knows he gets attention) you can't really change this. I would accept it as a phase. Unless you can organise things so that he can use the potty in his room without calling out? It depends if he is able to manage getting out of bed, getting his pjs off etc. It's quite a big step to do it alone but he might be happy to have a go.
- he is becoming or already aware of being dry at night and wants to stay that way. He might have initially not been thinking about it therefore the 4 weeks of night dryness without issue, but then once he thinks about it it can hover in his mind, niggling at him that he wants to be dry and that can lead to too many calls for wee. He just wants to be successful. I had a couple of years of DS not waking in the night to wee and then when he was older he started doing it, he was getting annoyed with the wee and said it was disturbing his sleep, he was often tired due to getting up in the night to go to the toilet. I didn't tell him he couldn't go but I did tell him that when he wakes in the night if he just turns over and goes back to sleep his body knows how to keep the wee in, kind of reassuring him that his body will manage and his head doesn't have to take charge by getting up to wee. Not sure if that makes sense and I don't think it's something you can force LO to understand but it worked for my DS and he got more sleep again.
I also found with my DS that he understood things I didn't think he could possibly understand, I'd mention things thinking 'no way will he get this' and then he'd surprise me by totally getting it.
There is lots of developmental sleep disturbance around birthdays so it could just be that.