Thats good. I had read somwhere thet the extroverts would rub on the end caps on the rails.
No bid deal if they do. Trim the rail caps to clear or trim the rails and re-mount the caps. Take about 5 mins to trim the caps with a dremel or 1 hr to trim rails and re-install the caps.
If you go with Extro's get the Micro-Belmont ones, they are a few more $$ but are wayyyy better. IMO