Low Coolant dash indicator '99 SL2

Every so often, the low coolant indicator flashes on the dash. Actually, 2
lamps flash simultaneously - the Low Coolant and Temp lamps. The owner's
manual warns of a low coolant condition and to fill the reservoir.

Ok, I check the reservoir and the coolant level is right where it should be
( inbetween the low and high marks). This is the first GM car I've owned
and it has DEXCOOL in it. The color is a pinkish red. It looks clean. The
temperature gauge needle stays in the lower half of the gauge while driving.

Ok, so if coolant level is good and temp is good, why the flashing
indicator??

Electrical short maybe?? My fuel gauge doesn't work 99% of the time (it's
always on Empty). I believe that problem is a short (seller put a new
sending unit in just before selling it to me and it didn't fix the problem).

Any ideas?