I had a 1-time ischemic finger and had an ECG (normal) with no previous history of raynauds. I'm 55. Should I pursue any other tests?

Yes. We have not had an answer yet and an ECG is not the only test. If is in one finger one must consider local vascular problems in the fingers, arm , etc on that side. We must eliminate the possibility of blood clots, emboli, trauma, smoking if you do that, you need to clarify why it happened.
Ischemic finger. I would. If you truly had an "ischemic" finger (ie., it almost died from lack of blood flow), i would want to be checked for certain rheumatologic conditions that can cause vasculitis (scleroderma, wegener's, polyarteritis nodosa, lupus, etc.) and for cryoglobulinemia (blood clots in the cold). It may just be "raynaud's disease", but it is severe; treatment with a calcium channel blocker may help.