Yup, I am talking about the screws that hold the action into the stock.
Before I panicked too bad, I'd shoot it again, maybe with some different ammo or factory ammo, to verify your groups are the rifle's problem and not the ammo's.
Only other thing I can think of is that maybe you nicked the muzzle crown when you cleaned it. That could cause some problems - might want to look at it with a good light and a magnifying glass if you've got one.