My girl Cody had a lump on her side last year but it was soft and movable and the thought was that it was probably a cyst and not a lipoma. We left it alone until it started growing larger, at which time the vet did a simple aspiration and found that it was fluid filled, so easily drained. Unfortuantely it kept refilling and as there is a high incidence of infection with repeated aspirations, we had it surgically removed. Although these lumps (fluid or solid) may be small, it takes a large, deep incsion to remove the sac and I was so sad to see her huge incision line post op. If it's benign and not bothering him, I too would say let it be I would however discuss with the vet the possibility of any future complications, the liklihood of them growing larger and what course of action might be taken then, just to ease your mind. Lots of well wishes for your Oreo! Please keep us updated! Sandra