Well gents:
Maybe it if different in the newer B737s but on the -200 according to Boeing (and they probably should know) the FEEL DIFF PRESS light is and I quote
"Armed when the TE flaps are up. Illuminated (amber) - indicates excessive differential pressure in the elevator feel computer"
According to my study notes this is the case for ADV aircraft only on the -200 BASIC there is also a rudder feel input which has been eliminated in the ADV.
Like I say maybe it is different on the -300 and up but since I only fly the "Truckasaurus Rex" I cannot comment. So it looks like ADUBI is right :-)
Cheers
Canuck