My puppy Gus is 4.5 month old.
He is already potty trained very well.
However, there were 2 accidents. all done by my roommate who forgot to open the door for him. Gus peed in front the tv in living room. Our house doesn't use carpet btw. So, it's hard ceramic floor.
and I scrubbed real hard and use the enzyme cleaner. But, now once in a while he would pee in front of the tv.

Is there a foolproof way to undo the accident?
Now, he once in a while would pee over there (especially at night). During the day, he would pee outside.
He has no water access after 7 pm. and I would take him pee after he drink and eat..
But, later at night he would go to that spot.
Honestly however he did well about 90% of the time..
I wonder should I take his water access even earlier (like at 4 pm)?
Is there such puppy being afraid of peeing outside at night?
This only happen during the night BTW.
how should I go tackling this problem?