its usually pretty simple to recalibrate ESC's
I'm guessing you have the VXL if so read this post for 2 years ago http://rcudev.rcuniverse.com/forum/fb.asp?m=7782241 it has the steps to recalibrate it

and Savagejim its not really strange he went from 50/50 to 70/30 the trigger goes farther forward which would be reverse from its stock 50/50 setting. I've had it happen on every radio I own when I swapped the throttle ratios and its fix is always as simple as recalibrate the ESC