5 speed sliping?

So heres my situation, I have a 2010 2.7L with the 5 speed manual. Going to work today i thought i caught a glimpse of my tach doing something strange while entering the freeway. basically i was in 4th gear, accelerating pretty good, and out of the corner of my eye saw my tach jump and then settle back to normal reading while i was under constant acceleration.

so this afternoon i decided to test it out, i was able to recreate it a couple of times, but not every time. im in 4th gear, running at about 2500, accelerate pretty hard, the tach revs to arond 3500, then backs down to normal and accelerates normaly, all while under constant pressure from me on the gas.

Is this normal operation for these manuals and i have just never noticed this before, or is my transmission slipping.

trucks got just under 50k on it, replaced the tranny fluid with redline mt-90 a couple of weeks ago.

 

Time for a new clutch.

 

bump?

 

Found the TSB, sounds like its my issue.

http://www.tacomahq.com/758/tacoma-tsb-5-speed-manual-clutch-disk-defect/

anyone else out there have any info on this, dealer quote was about 1500 parts and labor to get it done out of warranty.