Maverick is about 6 months old? It could be one of several things:
1. It is possible that he has a UTI. They're not that uncommon, and they do cause both increased urination and a need to go "right now". So if you have further incidents or notice any sign of an infection, a vet visit would be a good idea.
2. At six months, he is entering his adolescent phase. That's a time when a great many dog owners discover that their puppies don't actually fully understand the concept of housetraining until they're around the 6-8 month mark

Fortunately, a short re-run of potty training 101 is all it usually takes to restore order, and to finally cement in your puppy's mind that pottying is indeed an outdoor-only activity. So go back to potty training basics, and you should soon have him back on track.
3. I don't know whether Maverick is neutered or not, but if not, then there is a possibility that this is a marking behaviour. Again, as an adolescent, this is a common age for that sort of thing. Especially with another dog in the house. The simple fix for that is neutering.