I haven't noticed the texture on a straight print, but I have seen the texture appear during a bleach and redevelopment toning process. Maybe moving the print a little during development would minimize this effect. (This particular print was from a large run and I might not have agitated it much if at all).
Does having the slot very clean (not easy!) make a difference?
I'm not sure what the cause is - I've tried agitating regularly throughout the dev cycle, cleaning the devil out of the slot, and so on, but it seems to happen every few prints regardless, and it was only getting worse as time went by. Which coincided with but was not directly contributory to my move to alternative process printing. I haven't used the Nova in probably 3 or 4 years now.