Compact Gun Scope

I have a Gamo Whisper with a "Air Venturi Ram Air Gas Spring" modification with a "CenterPoint Power Class 3-12x44mm compact rifle scope" and it seems like at random times the scope is all of a sudden off center anywhere from 1 to 8 inches at about 40 yards.... (no its not my shot)

The reviews on this scope said it was of solid construction but this is my first air rifle with a scope. Any ideas? I also heard that the kick on air rifles are harder on scopes than "regular" guns, why is that? Is the kick of the Gamo Whisper screwing up the optics in the Century Point?

If it needs to be replaced, what are the best names in air rifle scopes for durability to the shock of the kick?

Thanks in advance.
EDIT: I was in a secure sitting position and the rifle was in a secured non moving position. There was no wind.
And the scope has been tight the entire time. I check it when it fires off center and it is not loose at all...