I removed the sole plate and found no deris, put all back together and still out of square, I'll get a pic shortly as you can actually see from the front that it's out.
I tested it on a few pieces and found it to be around 0.5mm out so set at 3mm would take 3mm one side and 2.5 the other.
I haven't used festool servicing yet so am weighing up my options, should I just send it in? It's still under warranty but it's a tool I use pretty much daily so I'll end up having to buy another whilst I don't have it, or I was thinking the the problem must surely lie with the sole plate or the adjusting screw, which I could buy replacements for really cheap anyway.
Obviously since i'm still using it you can see the problem isn't dire but still an annoyance , I tend to use it with 35mm doors so since it's not using the full width , the door edge isn't out as much as the full 0.5mm that the plate is out by, but if you were to make multiple runs from the same side of the door eventually the angle becomes very apparent.