I also reckon it sounds like a control thing. My son does similar. If he's asked he will often say no. 5 minutes later and he says he needs to go. He likes it being his idea😄 hopefully, if your son doesn't like being wet he will start to do the same!
This had made me feel a lot less insane about it all 😂 tbf to him we bought him a new pair of lightening McQueen pjs today and when I put them on him he didn’t want to get them wet so he told us everytime he needed to wee, I joked with my partner that he will be wearing them for the for seeable future 😂
My son went through a similar faze a month or so into potty training and think it was out of stubbornness. I stopped asking completely and left him too it and 2-3 days after he started telling me everytime. 1 yr after potty training he will still say no everytime I ask him then 5 mins later tell me he needs to go 😂