i have a 00 civic si, pretty much stock. i have lately been experiencing what i think is the clutch slipping. i felt like giving it a little WOT one day on the highway and noticed as I shifted from 3rd to 4th, my car seemed as if it didn't shift gears, it would stay at the high RPM for a bit and slowly crawl it's way back down. also, sometimes while driving in 4th, i feel a bit of hesitation. is this definately due to clutch slippage? It doesn't always do this, so that is why I ask.