Clutch slipping at 4k on highway in 4th gear???

[BYprodriver]

Originally Posted by redciv1

So this morning I was getting on the expressway and coming down a ramp. I was in 3rd gear and gassed it to accelerate onto the freeway. I go to shift into 4th gear and realize the tach is moving slowly up in revs at 4k but then slowly goes down about 200 revs and then starts to catch and accelerate. I thought maybe I left my foot on the clutch at top of pedal. I then go to shift into 5th gear and the same thing happens. At this point I know it's not me. Traffic slows and I down shift to 4th again and the same thing happens.
Is there any adjustments that could be done or does this sound like the begining stages of clutch replacement?
Ironically enough on the way home from my son's parade, I did a 4th gear pull and no slippage.

You may need to bleed the clutch slave cylinder with fresh fluid. (Brake fluid)