Nope... unless the scope is loose?

Ah... that could be it. When you boresighted it, did you make sure that the scope was firmly (and I mean firmly) attached? If the rings are loose, then a wobble that may be unnoticeable at 50 yards could be more evident at longer ranges.

Otherwise, the only other thing I could say is check for a crack in the stock or something like that. If there' s nothing wrong with the gun, then, as they say in the technology world, it' s user error. You need to hit the range that much more often. 3-9x should be plenty of scope for 200 yards, much less 100.