I've got a 1987 K100RS with just under 31,000 miles on it.

While riding tonight, I noticed that my downshifts were getting a little rough. What I mean by this is that it was getting a little harder to push the shift lever down to move from gear to gear. Before tonight, if I simply placed my foot on the top of the shift lever and pulled in the clutch, the weight of my leg would cause the downshift. While riding tonight, I had to actually apply downward force to the lever before it would engage the next lower gear. The clutch felt no different, nor did the feeling of an upshift.

Does anyone have any thoughts that may help me? Is this something I should be worried about?