lateral separation?? wtf??

ok, this thread starts on friday....I put on new 5100's in the rear and rotated the tires, back to front, and front to back....I noticed that after I rotated the tires that my truck was pulling to the right, and the steering wheel was off centre, and in order to keep the truck from going way to the right, I had to pull the steering wheel left, obviously. This lead me to believe that I was in need of an alignment.
Fast forward to saturday. I drop off the truck, tell them my concerns about the steering wheel, etc. I come back and pick up the truck, drive away, and wouldn't you know it, IT'S WORSE pulling way to the right, the steering wheel is off centre STILL. So right away I take it back.....and tell the manager that it's worse, blah blah...he takes it for a spin, and starts telling me that the steering wheel wants to walk to the right, and starts going on about lateral separation on the passenger side tires.....wtf???
My question is....how could I have it? and in the end, they were able to align the truck properly, I mean, it doesn't drift, pull, tug or anything of that sort....so of course I am wondering if they tried to pull some shit on me, in order to get some new tires (the tires have 6/32 on them) Any and all opinions, insight, etc would be appreciated, and FYI this is the second time that I have had this issue with this shop, they had to realign it the last time twice...and the only reason I keep going back is because I have a lifetime alignment and plan to get my money's worth, and yes, I have almost gotten it....END RANT