on my 2010 I seem to find that on a light I waiting this will happen. I pressing down on the pedal when all sudden I can feel like the pedal is pushing back up on my foot. like if build up of pressure.

 

I'm not all that knowledgeable about that end of the brake system, but I would suspect a problem with the brake booster. It sounds like ambient air is leaking onto the vacuum side of the booster drum. It's remotely possible that you have an ABS problem, but an ABS problem would usually give you a CEL/MIL or the red BRAKE light would remain on after you release the parking brake.

Is the pressure buildup accompanied by any sound? And does the pedal feel normal the next time you stop?

 

it sounds normal and feels normal. just it seems to me pushs up like a couple inchs at most when stopped for a while. no cel or lights on,

 

If that's the case then I'd lean towards the brake booster system. It could also be a vacuum problem elsewhere that's creating this symptom.

 

van runs like normal just slight more fuel usage but that's probably more city and short trips lately while cold. guess I just keep a eye on it. rear brakes been acting up servicing them every 20,000km so not sure related aswell.