Congratulations, Kimmy! This certainly is a surprise. I think Phred's housetraining advise is right on target. Also with all the excitement of new people, new environment, and playing with a new buddy, last night had to be a highly unusual situation for him. If the peeing continues to be so frequent, you might want to talk to your vet. Don't know much about urinary track infections in male dogs, but in a female that would be a sign.

By the way, how are you feeling?