Your dog may love the extra walks and playtime right now, but having people around more often can also stress him out. If he startles easily and drools more these days, he may be dealing with some serious doggie anxiety.
First off, I'll say that I LOVE dogs. I have dogs, honestly dogs make my day. I also keep them on leashes if they're outside. I had an experience that made me so ANGRY, not at the dog, but the dog's owner.