I never really understood how the payouts worked on the slots. I always won when nothing looked lined up, and when i got stuff lined up (got something that looked just like yours) and didn't win.
I had it line up three bars right in the middle and gave me nothing. I've also had it give me cherries that didn't pay out. I would say I'm suprised. However, I'd be more suprised if a casino in a post-apocalyptic world didn't cheat its customers.