This may actually not be a problem. I know of a few differnt vehicles that do this on purpose. A few Fords do it as far back as 94 even(explorer 4.0(not all do it tho, kinda wierd)). This is done to keep you from accidentaly doing this while not under load because as Cadd stated above it is BAD for your engine.
This may not be the case with your engine, but I know some are built to do this on purpose.
Jer