They might have sprayed with the intent to make an adjustment if it was way off, the mechanic might have decided to "cheat" when he saw how close it was. Most shops do pay on a commission rate, so the faster a job gets done, the faster the next one can come in. Unfortunately, that can cause some mechanics to take shortcuts.
As far taking the shim out, you can do that yourself fairly easily. You'll need to jack the truck up, supporting it by the frame preferable for better access to the nuts. Then take both nuts loose, but not off, the front one a bit more than the rear, to allow for the shim to be able to slide out. Then simply tighten them back up. You will toe the right front wheel out a bit, but that can be easily compensated for as well. That procedure is covered in depth in several threads on the site.
