We're back from the vet. The lump is too small to do a needle biopsy at this point. Since Phene needs a dental, we're going to remove it and send it out for analysis when the dental is completed; probably in February, unless it changes or his teeth seem to worsen. Due to the size, location and consistency, the vet didn't seem terribly concerned but he would like to get it checked out when it's either bigger (if it's bigger) or during other surgery (or dental).
Another thing I'd noticed about Phene is that he'll no longer climb the stairs in the dark. The vet checked out his eyes and showed me changes in his lens. He said that it's difficult to tell at this point whether it's just a matter of aging eyes or the beginning of cataracts, but he believes that he is in fact having difficulty seeing in the dark. His vision is something else I'll have to keep an eye on.
Thanks to all who offered advice and good wishes