rebuilt tranny clicks when cold

[WatchItExplode]

I've put about 3000 miles on my tranny since I had a Shep rebuild done. Just a couple days ago I started getting a clicking/grinding noise when I shift into 3rd gear. It only happens for about the first 10 minutes of driving, and then it goes away. I can feel it in the shifter more than hear it, but it feels like it wants to grind but instead it goes into gear after one "click".

I wanted to ask just in case this is the type of problem that gets worse over time. Should I change the fluid? As per Shep's recommendation, I'm running 1 quart of redline heavy shockproof gear oil and the rest Pennzoil Syncromesh in my transmission. Anybody know what the problem is, or if it's even something to worry about?

 

[TwoLiterLaser]

If the problem is internal then it is probably a synchro biting the dust. But I would look to external causes first such as clutch cables and tranny arms. Do you beat the car? By this I mean do you shift it fast and hard very often?