Dog wetting Issues

Question
Hi -  I am the proud owner of a 2 year old cocker spaniel.
His name is Buddy and, for the most part, his behavior is very good.   However, lately he has been peeing in the house when a new person is in the house.  We think this is wrapped up in either fear or nervous excitement, or both, but we do not know what to do about it and how to correct it?

Other context:
He has done this occasionally ever since he was a puppy, but it seems more consistent recently.
He is house broken and generally does a great job waiting to go until outside.
He is home all day.  My with and I both work.  We take him out in the morning at around 7 PM.  A dog walker comes by an noon and walks him for 30 minutes.  Then we are home by 5 and immediately take him for a long walk.  We take him out at least one more time before bedtime.

Answer
Is your dog neutered?  If not, he could be urine marking to establish that the territory belongs to him.  

Some dogs do what we call "submissive urination" or "excitable urination".  In that case, the wetting occurs when the person enters the home, there is excitement, or the person attempts to greet the dog.  Cockers are prone to this behavior.  The solution is to make all greetings very low key.  People can come in, ignore the dog, and wait for the dog to make the first overture.  It helps not to stare at or reach over the dog.  Patting can be done under the chin, once the dog is relaxed.