That's about the same as me yesterday then Rob - 1MOA is about 1/2 inch at 55.
Don't know whether it's down to atmospherics, differential expansion, something else or a combination, but I'm happy enough that I can check zero on the zero range, adjust to suit the conditions and carry on.
I have noticed something with shooting a springer this season - if I fluff up the trigger technique even slightly then I will shoot high and right by quite a large amount and my 2nd stage does feel very slightly heavier in warmer conditions.
I wonder if some of the reported problems we're seeing in this thread are more to do with technique than anything major shifting on the gun. There's no shame in it, springers are fecking difficult to shoot consistently.