The light is coming on because of an "overcharge" indication. At those revs the alternator is puttin out current at the upper limits of the electrical system.
At least that was the problem with my old Mercury at 95,000 miles. The Voltage Regulator got stuck at peak output & I had to drive to the dealer with all lights, A/C, & everything turned on to keep from over-charging the battery. Dealer replaced the VR & the car ran fine ever since.
Should not be something to worry about unless you run above 6k rpm for extended periods.
