Clutch

[N106FM]

Hi
I have a 2004 Kia Optima. When the engine is hot the clutch will slip and there is no play on the clutch petal. When cool the clutch is tight and there is about 1/4 inch play at the top of the petal. This is started at about 12,000 miles. The car now has 30,000 on it. I have babyed the clutch since the car was new.
The problem was checked by the dealer at 12,000 and at 28,000 and could find no problem and claimed that the clutch was not slipping.

Anyone have any ideas?

Thanks

Mike