Bad transmission sensor?

You might give Allison a call to determine where their temperature sensor is located.

There is no "here is where the chassis maker's sensor should be. Some are in the outlet line from trans to trans cooler, some in the return from the cooler.

Allison help line 800 252 5283. Call them with your Allison SN.

Texas,

This was after about 150 miles so I'm pretty sure it would be above the lower digital temp limit and outside temps were around 60. I did check for codes but there were none. I believe you are correct in that the analog in a Freightliner item but would they have 2 sensors, one for the allison display and one for the analog?

How far had you driven when you tried to check oil level? It takes many miles to get the transmission up to operating temperature. And I BELIEVE (do not know for sure on Freightliner chassis) but the oil temperature gauge on the dash is likely NOT an Allison component, but rather a Freightliner one. Depending on the sender's location, it may not register if ambient temperature is cold. Or it may take 50 miles or so.

Did you hit the up/down arrows again to check for diagnostic codes? Were there any?

You should go by a Freightliner shop. Or Allison, if that is what you have, dealer.
Should call or drive toad first to find out about problem.