did you recently recalibrate the esc?
Might not have been getting full brakes.
http://www.youtube.com/watch?v=zYam5l84uEA
in that vid at 40 seconds is the sound i think your hearing..
Benjamin White
R/c Monster Team Driver
Jq the car, LST, Sportweks turmoil pro
Unconventional Techniques, Superior Results