58yo, m, healthy. noticed a bone bump behind right ear closer to the top. lump small, not visible , but palpable. can be tender to touch. please advise?

If you do not have any other symptom that suggests infection around your head, ears or possibly systemic signs like fever, I would suggest to probably watch it in the next week or so. I expect it should go down by itself. It may be lymphnode reactive to minor infection that the body could contain by itself. If not subsiding or getting bigger in about two weeks get it evaluated.