Just returned from the vet. She is pretty certain it's a lipoma (fatty tumor) and says it's very circular in shape, soft, under the skin and moveable- which is why she is 99% sure it's a lipoma (which she also confirms is very common in mid-aged Goldens). She did say that the only way to tell for sure is to have it biopsied- and she says it's so small that she would prefer to just remove the whole thing to send it all for biopsy. I had inquired about getting his teeth cleaned soon anyway so she suggested doing it all at once so it's not necessary to expose him to anesthesia twice. She assured me that it's nothing I need to do urgently and can wait a few weeks (while I save a little $ for the added expense) and that if it was even slightly concerning to her she would insist I do it urgently. She says most pet owners don't even notice these bumps and lumps but I think I am just really overly keen on my pets.
I can't help it it's in my nature. But I am one who must know in order to have total peace of mind so I will opt for the surgery as soon as I can swing it. So within a few weeks Murphy will have a biopsy and removal and some really clean teefies.
Please keep him (and me) in your thoughts and prayers. Thank you to all of you for your input, support and help!