My three year old jack Russell has a complete obsession with the pillow on my bed. At every opportunity he will go into my room and be "extra friendly" with it. He has been neutered so I cannot understand this. Does anyone know why he does it. He knows it's wrong because as soon as I see him he stops doing it.
Some neutered dogs (even spayed females!) will just have a "special toy" or object that they do this behaviour with. Its not a sexual behaviour, more likely excitement or something they do when happy and around that object. It may be that it smells like you (don't be freaked out by that!) and so he feels happy with it, and thats the behaviour that comes out
If you want it to stop you can limit his access to your room - shut him out all the time. Or throw the pillow out and see if he stops once you have a new one. You could also try just giving him the pillow as a toy, and getting a new one for your bed
Overall I wouldnt be too worried over the behaviour except that its a bit odd obviously. Some dogs, as I said, just have that one toy they really, really like