Puppy Started Weeing Indoors Again?

Jack was castrated a month ago and apart from healing slower than expected due to suture rejection, has recovered very well. During the same time, we looked after our friends' Beagle for two weeks while they were away on holiday. All has been fine, last check at vet's (a week ago) was good. Beagle went home to friend. But in the last few days Jack has started weeing indoors. He has always sprinkled when excited or a little nervous, but this is puddles - for no apparent reason.

As today, the door has been left open most of the afternoon, he has been playing in the garden with our daughter and then outside with my husband. 15 minutes later we find a puddle in the hallway! Does this mean we need to start from scratch with hourly visits to the garden until Jack is retrained?

By Sandi