I have an IX, w/ 13000miles, and it's been running great until this morning, I noticed that my RPM surged for a few hundred revs when I clutch-in for an upshift from 4th to 5th gear!! It seems to happen only when the car is in boosting and having RPM > 4000. It won't do that if the RPM was in 3000 or lower.

My clutch still feels strong and solid, I don't think I'm getting a slipping clutch...

Any help or suggestion would be highly appreciated