It looks like he got your truck aligned, right? If so, I wouldn't worry about it.
I've heard of places that won't even touch lowered vehicles, but it's not like you have some undriveable lowrider or something.
Besides, even if your camber is a little bit negative, that's really not too bad. It has to be pretty extreme to make your tires wear badly.
In any case, keep an eye on how the truck tracks and how the tires wear, just to be safe.
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