Camber adjustment ?

[Chrispbrown36]

So after putting new tie rod ends on I took it to a tire place up the road from me to get an alignment done. I have used them a fair amount of times since they are so close and they have always been straight forward with me. Today on my lunch break I called to see if they got it done and the owner wanted to talk to me. He told me that the camber needed to be adjusted but "those trucks weren't designed to have the camber adjusted." Not having any knowledge of camber, I pressed for causes, parts that might need to be replaced, etc. He told me over the phone that nothing can be done. When I went to pick it up I talked to him again and when I pressed it he mentioned shims, but said that it would be a BIG job if it even made a difference. I found this all hard to believe.
He gave me the print out on the alignment and it lists camber on the left at positive .4 and the right at negative .6. He said he didn't think that it would cause any major issues, but "I wouldn't even mess with it if I were you." So what do you guys think? Please feel free to educate me on camber and how to correct it.