Wrench light goes on on 2008 Mercury Sable

Two separate times while we were traveling up steep hills in the heat, the little wrench light has gone on. When going down hill it goes back off, and it has not come on since. The car seems to be running great. Do I have a problem, and if so how big?

Asked by for the 2008 Mercury Sable
See what the light means it is in the instrumentation section of your owners manual.
It says it has something to do with the transmission.