Anytime something foreign gets into the oil system there is a risk it can clog or block the flow of oil into any area of the engine leading to an area that no longer receives lubrication. This can easily cause overheating and possibly leading to engine failure. How far down the hole did it go? I would every attempt to get it out. The oil filter area is part of the magneto cover on these engines. If worse comes to worse remove the cover and hopefully gain access to the o ring before it causes catastrophic failure.
