@ Bluesman - Because the Spit aileron trim is set on the ground, it's only perfect for a specific flight speed and throttle setting.
A combination of rudder trim and throttle setting will reduce the effect to a minimum, although it shouldn't really be possible to fly the Spit totally 'hands off' for any great length of time.
You'll also notice that in a fast dive, the rudder trim goes way off in the slip indicator, needing a lot of re-trimming on the way down, although I find it easier to just press the pedals.
I certainly wouldn't call this a bug, more of a flight characteristic.
