I also had the Nuke Ach without actually doing anything. I think I was just searching for a new car at the time when it popped up.
I've noticed more "handy bugs" while free-roaming accross central park actually. When I was still burning trees I accidently wounded myself in the way you start to bleed to death, was low on supplies and to lazy to do anything about it, so used me last 2 bottles burning down two trees, died on the third (out of bottles, out of time, baddies).. and low and behold when I get put back I got all the materials back from the last 3 trees that I burned!
I noticed it later on again, dying inbetween burning trees can give you inventory items back. Bit lame, but at the time it was handy (was in the central area you can only reach through one small walkway over the water and no new materials available.
"Which side are we on? We're on the side of the demons, Chief. We're evil men in the gardens of paradise, sent by the forces of death to spread devastation and destruction wherever we go. I'm surprised you didn't know that."
- Col. Tigh (BSG)