I had this same issue when I owned my 2003 Tacoma. Maybe I just intentionally try and find something wrong with my truck. On level ground with equal tire pressure in all four tires, the bed on my 2005 Tundra seems to slightly lean to the right rear. It's not horrible but you can see it with the naked eye. With my previous truck, the dealer said this is common because they bind down the trucks too tight when they transport them. I would say that the right rear corner of my bed seems to be about one inch low. Is there a fix for this or am I just anal?

 

If this is what I'm thinking of... this is commonly noticed with the pickups. It is normal and the popular belief is that the suspension is a bit off to take into consideration the driver and the tank of gas.