Yeah - lift or no lift, suspension can get out of alignment. Even bone stock cars need alignments every now and then. Also, even if the rear end is a straight axle, that doesn't mean it's always going to sit straight (in relation to the front wheels). Once you disturb the rear end suspension by taking it apart and modding it (installing blocks, AAL, full leaf, even just angle shims) you moved the rear wheel positions relative to the front wheels. A proper "full" alignment takes care of the small differences.
And I agree with
@smj999smj - the OEM Nissan camber bolts are much better than the cheaper 1/2-cut aftermarket versions. This is where I bought them from (price went up a little, but I bought mine 2 years ago):
Genuine Nissan Xterra Adjustable Camber Bolts (says Xterra, but it's the same parts for the Frontier)
They sell the whole "camber kit" as a set, that's where I bought mine awhile back after pricing it out at a local dealer that wanted to charge me $130 and tax for the same parts.
Aftermarket kits usually use a flat spotted washer and a 1/2-cut bolt, where as the OEM Nissan eccentric washers ride in a slot in the bolt that makes adjustment more accurate. Personally I'd recommend to pay a bit more for the OEM Nissan I'm sure someone will chime in with their own "yeah but I have aftermarket camber bolts and have had no problems" now that I said that (LOL) but here's a pic showing what I was describing, so you can pick for yourself what you'd rather put in your truck... left is aftermarket, right is OEM Nissan (not my photo):
https://imgur.com/a/pfVmj