I've checked through the forums and I've seen some problems that sound similar, but mine is different enough I figured I would ask it separately.

When driving at highway speeds occasionally my car will appear to drop out of gear for a split second and the green D light will go off for about half a second. After this happens the car will continue to drive normally, shift normally, etc. and the problem will not return for days, weeks, or even months.

The other posts that sound similar to mine seem to indicate a light that continuously blinks, but mine does not do that. It is also not accompanied by a check engine light and it only appears to happen when it is warm outside.

This problem has been happening on and off for probably about 4 years now but has never been significant enough (and I've never been wealthy enough) to check out. I'm asking now because a friend would like to buy my car and I'm trying to get the best idea I can of any potential issues with it so that I don't screw her over. Any help or ideas on this would be greatly appreciated!