I know my Pookie Bear has to go out at least every 4 hours during the day or he will have an accident. I have no idea why because like you said, he holds it all night long!
Sorry I am not of much help. I also notice when he's in his crate he gets no bedding, because if I give him one he will pee on it at night. He will only hold it without bedding. Part of me thinks it's marking, the other part thinks he is just smart enough to know it absorbs the puddle
He will get over this, it's a puppy thing, ours is getting better at it but will still go in the house in the daytime if we don't watch her. But she is getting better at it and so will your little guy.
Piper may also be upset at being left behind. Buster will sometimes pee the laundry room floor (very small pee) when Ruggles gets to go someplace without him. Buster has no reason to pee the floor because he has a pet door and can let himself out.
Chuckie was doing the same thing and we found out he had a bladder infection. Its been about a week off the antibiotics and havent had a crate accident yet. He showed no symtoms other than frequent urinating when he was awake. He is just about 5 month old now.