Chances are the bipod is exerting pressure on the forend which is exerting pressure on the barrel. Take a dollar bill, fold it in half and attempt to pass it between the stock and barrel along it's entire length. It should travel unhindered. Now with the bipod employed exert a little downward pressure on the rifle and redo the dollar bill thing.
Anything hanging up?
Action screws torqued to 65 in/lbs?
Pull the action from the stock-any indicators that anything is moving around?