Any updated on this issue?
Did switching out the brake sensors rectify the problem?
I'm having a strange E-gear issue with my 2008 LP640 coupe as well. Gearbox runs fine when not switched on and runs through all the gears with ease. From what the dealer tells me, the gearbox changes gear fine when its cold but the gearbox light comes on when it gets warm and refuses to get into gear. Dealer said the Selespeed sensor is throwing cold and they'll have to take out the whole drivetrain to replace them.
Did you have any fault codes on your's when you had the issue?