When letting off on the accelerator the headlights dim briefly any ideas what might be happening ?
I have read of others with this issue, they said it happens when breaking and the traction control kicks in. There is a recall on a hydraulic break swith could this be related ?

 

It isn't anything I would worry about. I have seen many different cars do the same thing. Usually what is happening is there is a momentary delay in the alternator's ability to provide proper power to the system. If you let off the throttle the rpm's drop and so does the alternator output. If another electrical system kicks in then it will draw additional power from the system and the alternator will have to compensate. This is assuming the dimming of the lights is fairly minor. If they dim really badly then it may be an actual issue with the alternator going bad.

 

Break = to separate a whole thing into parts; "Don't drop the glass or it will break."
Brake = to stop; "There is a recall on a hydraulic brake switch, could this be related?"

I agree with malebolgia, it's probably nothing. Do you have stock headlights or aftermarket bulbs that are of a higher wattage? It can't hurt to get the alternator checked.