It could just be a training relapse. You say there are no changes in the household, but I bet they've grown used to having a dog that's housetrained and grown a bit complacent too early. An 11-month-old goldendoodle is still very young and still shouldn't be left unsupervised for too long without the owners wondering what he's up to. If he's wondering away from the room that a family member is in then there could be a reason and they should go follow him and see if they catch him sniffing for a spot. I don't know too many house dogs who prefer to be out of the room that the family is in unless they're looking for something to do out of boredom or are looking for a place to hide that they're going potty indoors. I think they should try just taking a step back and letting him out more and supervising more and not trusting him so much yet.