I've got about 2500 miles on my GSR and recently I've noticed that the shifter is noticably harder to move between 3-4 than between 1-2... whether the car is off, cold, hot... anytime. No problems actually getting it into gear or anything, just requires much more effort than it should.

Could the linkage between the shifter and the transmission be bent alittle thus rubbing against the plastic and causing the extra effort? I have had an occassional mis shift were I was going for 3-4 and missed the gate on the first try... I was thinking that may have bent the linkage?

It could be a few different things. It's possible that you bent a fork. That's probably the most likely. Or it could also just be a bend like you said in the shifter cable. Either way, hopefully you're not modded too bad so that way the dealership can take care of it.