Alignment: Camber adjustment

After my second visit to my local Firestone to try to get my camber adjusted to zero, my left front is still just outside of spec (-.3), when I specifically went in saying I wanted to get the camber to zero (or a hair positive if anything I'd guess would be better). I get told 'camber isn't adjustable on your truck.' I tried to press to make sure he didn't have caster and camber mixed up, as can be the case, but realized I wasn't going to get anywhere with him so took my keys and left.

I'm being a tad paranoid about the alignment for 2 reasons - 1, my last set of tires ended up being a noisy hunks of rubber because I had a bad alignment for a while and didn't catch it which caused some abnormal wear, which were just replaced with a new set and I'm attempting to avoid a repeat - and 2 - I'm about to embark on a long road trip where a bad alignment could do just that in short order.

The newest 'Current Measurements' read:

Camber: left = -0.3, right = -0.1
Caster: left = 3.5, right = 3.5
Toe: left = 0.02, right = 0.07
Total Toe: .09


Of course, if I compare the 'Before' measurements of this print off to the 'actual' measurements from 3 weeks ago, either I hit something to throw the toe out and the caster and camber adjusted themselves - or their machine just isn't that accurate.

So, do I have reason to be annoyed, or am I just being overly nit-picky?