I have this happen when i upshift too early... mainly into 2nd and 3rd gear. Only really happened my first few days of riding. This is also my first vehicle with a manual transmission. Learning curve i guess for me. I did not want to go too high into revs. since then i have found that i can go higher in 2nd than i thought. Just taking baby steps. I have found that 5k i upshift pretty smoothly, below that... it is not exactly smooth. Mostly though I am trying to listen more and more to what the engine tells me as I get used to it.