You do tend to slide a little bit with waterproofs on - but you should get used to it after a while. Especially if you are on a new bike too. Is it a completely new style of bike to you as you may find your muscles are still getting used to supporting your weight and balance (noticing it more so in the wer) but yeah if its a big problem then like do like Slidy suggests
I do find with my leathers on that I end up sticking to the seat too much in the dry, and I tend to move around the bike a bit, specially on track days.
(Although if its wet you shouldn't really be trying to outbrake Rossi
)