Oil gauge fluctuation...

I have a 96 XLT with 4.0 and auto trans.
Mileage is approaching 162,000. Since about 2 weeks ago I noticed my oil
level gauge will "flash" momentarily to bottom red, then return to the
middle position.
This seems to occur when its cold, and if I take sharp turns.
Since it always returns to the normal position I suspect the gauge, but
can anyone suggest possible causes?
I'm not low on oil, and nothing else seems unusual.
This "flashing" of the gauge can either be several quick movements, or
one that lasts for a second or two. It also seems to taper off after a
period of driving, but can still do it.
One more thing. I had my speedometer rebuilt about a month ago, so the
instrument cluster was removed. However, this problem didn't start soon
after that work was done.
Any ideas are appreciated. Thanks.

Randy

We're living in a world that's been pulled over our eyes to blind us
from the truth. Where are you, white rabbit?