Relapse in potty training?

[Kutay]

So I have a pug who just turned a year old on the first. It took us forever, but with patience and effort he was accident free and potty trained about 2 months ago... until now. On Thursday he decided he couldn't hold his pee (even though he hadn't really had any water since he went out an hour before) and he started peeing on the floor with no warning. I picked him up and he kept on peeing! Alright, I figured he was excited after his bath and just couldn't hold it. (Vet DID check him out and said there was no bladder problem.) Then this morning he poops on the floor after being taken out twice. My roommate's little sister is here, could it be excitement? He's been left in my room for a few hours at a time while everyone's out of the house- not a single accident. Both times he's had accidents this week, we were in the house. What can I do to make sure he doesn't keep relapsing? I understand pugs are difficult and to expect accidents, but I don't want him to revert to 1-2 accidents every couple days.