Doesn't it only lever once you get out the car and then every few hours so after you get out it self levels and doesn't for a few hours so what happens in the mean time open a door just to check
If it stays up with the tailgate open, it could well be a dodgy height sensor or connector. If you have the EAS software, look at the actual sensor readings, move it up and down a couple of times and see if the reading stays near enough the same.