that's looking pretty good Lewis
.
At your guider image scale, an RMS of 0.1 pixels corresponds to about 0.9 arcseconds RMS, which is OK. With the min motion set to 0.15, corrections will not be applied until the error reaches 1.35 arcseconds, so it would not have been called on to correct very often in those conditions. You might get even better guiding if you use a smaller value for this parameter. If you really want to check your guiding, use phd2 and enter your guider fl and pixel size - it will convert to arcsec and give you a guide graph that is more readily compared to others (and shows how much wander there really is - at your scale, the wiggles in the phd graph are difficult to make out). It will also show guide error RMS for each axis, which gives some idea of how much worm error there is in the RA.
However, the mount is definitely working well enough that the stars look nice and round at your imaging scale of 2.35 arcseconds (or 4.7 arcseconds binned), so you currently have a well balanced wider field system - the 4000 is probably a good choice with your scope and mount and the results look really good. Please, let's see more - sky permitting of course.