Yet another T5 question !!??

[jetuomi]

Hey all, I've searched for this first before posting, but, failed..
So, here goes the question:

Got my T5 rebuilt over 16000 miles ago (8 months ago), and its been great, it survived my first strip experience, shifts smooth, no noise (except that 3rd gear whine), BUT, if I go on long trips (like over 100 km's) without stopping or shifting for a while (staying in 5th), then I go to pass a transport truck or something and drop it to 4th or 3rd, and rev it to above 3200 rpm (has to be above 3200 rpm) then when I shift back into 5th and continue cruising, I hear a whining sound coming from the shifter (approx. area). It'll whine/squeal (sounds like metal on metal contact, but not too loud) until I pull over and turn the motor off. Fire it back up in 10 seconds, and all is good, in fact, I can rev it in 4th to 5000 rpm and no prob. Its only on these long trips...

Any ideas??? Could it be low fluid?

Thanks guys!!