Glenlek: the ball just has a mind of it's own
Just a theory. I think it's possible that wind and maybe other variables bleed over from one round into the next. Since I started clearing cache before every round, I've noticed less of this problem.
You should expect some vagaries until you get clubs with more 'precision,' but nothing as wild as what you describe.
Of course: (apologies to Duke Ellington)
It don't mean a thing if you don't get that ding. :-)
Hope this helps. GL