420 SEL overheating or?

My 1991 420 SEL has a little temp guage quirk, started today. Engine cold, start car, temp guage goes immediately to 80+ (C).
It then goes up a little as the engine works.

Normally of course it would be at 0, just below 40 (C) then stay somewhere between the 60 - 80 range (C).

I'm thinking possible temp sender? Maybe a static resistance reading on the sender that I can measure. Possibly beginning to fail and using the 80 mark as a starting point?

Any experiences with this issue?

thanks..... s-ball