Hemmen, I had 4 sets of shocks put on the front and 2 on the rear under warranty. This was over the course of about 55K miles. Several of them were leaking, and some just lost pressure. Have the service writer bounce the truck with his weight and then go bounce a new one, if there is a big difference he will authorize new shocks for you. You could also squirt a tiny bit of something up in the cover a couple of days before going in if they refuse to step up and honor your warranty. Whether or not you do that is up to you, I would not be surprised to get flamed for saying it either.
That said, fest3er is absolutely right that the stock shocks are JUNK. I got sick of having them changed and bought a set of Rancho 9000's out of my pocket when I could have gotten free OEM's. It was a great decision, they have about 50K on them now and still work great. Ride quality was improved a ton, and handling is good now. No more hopping sideways over RR tracks or front end bouncing 4 and 5 times over a big bump. They took a lot of the adventure out of driving, all in all I would pay for the Rancho's right off the bat if I could go back.