Hey guys

recently been having a bit of a problem, I'm taking my car into my tranny shop Wednesday but i wanted to see if you guys would have any time. so

When driving the car at normal operating temps and driving. I notice that sometimes when the car comes to a stop or when taken out of Revere, or anytime that the car idles. That i'll press the pedal to go and it will just rev up but not go. Like the Torque converter is locked, after like 1 or 2 seconds it will release and go like normal, i've only had this happen 4 times but it seems to be getting more and more frequent. At driving speeds and highway speeds it shifts smoothly and has good power, so it's not slipping. I told all this to my trans guy and he said it could be the main seal letting air into where the piston draws oil to contact the clutch plates?? I have no clue but i'm starting to get worried as these trannys aren't very good. Car has 156xxx km on it so it's pretty fresh. Trans oil is in good condition and it doesn't get overly hot. LIke i said it only sometimes does this but it did it today as i backed up and threw it in drive, it just slipped and didn't go as i pressed the pedal, and then it jumped into gear and went.

No clue what's happening.

Any ideas? you ever have this happen to you? the car is a 99 Grand Prix GTP Comp G.

Thanks