So I posted some time ago about how my husband did not want Gibbon neutered. I eventually convinced him and we had him neutered last Thursday. Gibbon is doing really well except for one issue. He started to have accidents in the apartment. He was fine through Sunday. Then yesterday and today, in the evening, he peed by the couch. He only does this once in the evening. He is fine in the crate - no accidents - when left for about four hours. And when leaving him for a longer period alone on Monday during the day, he was left in two rooms of the apartement and we left a pee pad and he went on the pad. So it seems like it is just that one time around 8:30ish the past two evenings. We take him out around 6 so it would only be two hours later, he would pee by the couch.
I have noticed he is drinking a lot more water lately and he used to be 

retty regular with pooping when we brought him out although the past couple of days, he isn't as regular. He used to go poop every time we brought him out - 3x a day - now it's maybe two.
I have no idea if any of this is connected. Of course, I do realize that the more he drinks, he probably has to go more but he normally goes on the pad. Is this behavior just a phase or something to do with neutering? Again, it only began after he was neutered. Any thoughts? I'm just a little confused. Thanks everyone!