Marking?

So Bacon is a 13 week old male French Bulldog and I'd have to say the house training has gone pretty well. He seems to get that he's supposed to pee outside. I try and take him out every hour and if he feels like he has to eliminate before that he sits next to the baby gate and stares at it until I take him out. I'll sometimes ignore him if he decides to do this within a half hour, to try and a) let him know that he can hold it and b) that I'm the alpha here.

Anyway, today we had Bacon's first puppy play date here at the house. Bacon had a blast, though he was a bit scared of the other dog. Anyway, I was sure to take him out a lot during the play date so he wouldn't get too excited in the house and have an accident. As soon as the other dog left Bacon made a big messy poop, which was expected from all the stress/activity. However, ever since the other dog left Bacon keeps peeing in the house. Something he doesn't usually do. I've read that dogs don't really get angry. But could this be the first sign that he's marking his territory? And do you think he'll keep doing this now that he started it? Or do you think after a day or two of not seeing the other dog in his own home that he'll go back to normal?

Thanks!