Thank you for your replies.
I was wondering about both the RA and DEC moving so quickly, which is also why I came here
I'm sure that the mount was not being bumped or touched in any way, and while there MIGHT have been a slight breeze, I was in a relatively sheltered area so I doubt that would have been a problem.
I did check the nuts and bolts, and the mount is on some large pavers so not going to sink into the ground any time soon.
I am thinking tonight I'll just do a few tracked subs with no guiding and see how that goes. At least it rules out something to do with the guiding system going crazy.
The mount is still under guarantee, however I'm still a little tempted to open it up anyway to do some cleaning. (It always sounded a little grindy compared to some others)
I have a few new ideas though, so thanks again for your replies.