100% potty-trained!! (Sort of...)

Okay, so we are about 6 weeks into the potty-training process and I am excited to be able to say Ayden is 100% potty-trained. Well, sort-of. The techniques I learned in my Stress Free Potty Training Book are working wonders. Ayden stays naked from the waist-down at all times when we are at home. The potty chair stays in the living room and moves room to room when necessary so it's always there as a reminder for him (both of these methods came from the book). He stays dry at night about 50% of the time, sometimes he even wakes us up to go potty during the night. About 2 weeks ago, he started peeing standing up and we thought it was about the funniest thing we had ever seen. Until this week when he started pooping standing up. Yeah, I'm not kidding. Leave it to my creative and spirited kiddo to change the rules up completely!! We are working on getting him to sit for his major business but are just very excited that the poop is making it into the potty!

Now for the sort-of part. So the naked method has worked wonders...but possibly has created a problem. Because just minutes after we put underwear on him, he comes to tell us he has peed. Or pooped. No idea why!!! As long as he is naked, we don't have to remind him or give him cues to go potty, he follows his own signals and does it all on his own. But just the fact of having underwear on makes him forget to read his signals??? I don't get it. So for now, he stays naked. Also, we have not been brave enough to take him out of the house without a pull-up on, but interestingly enough, he almost always stays dry while we are out running errands. It's just an issue of wearing underwear at home. I bought his favorite character underwear and tried the whole "Don't pee on Sponge Bob. Don't poop on Thomas the Train" theory and it didn't work. He immediately apologizes when he does it, but he does it every single time I put underwear on him! So I don't know if this is a defiance issue that needs discipline or if I am being too over the top...after all its only been a few weeks and he is really doing pretty fabulous overall. I just don't think we can take a naked child to Walmart or the zoo, let alone kindergarten!

Any advice?