I did an internet checkin for AA flight from LAS to LAX and got my LY boarding pass as well.
The problem was that I got 13F insted of my reserved 10K
When I arrived to LAX , I talked with the station manager and he told me
that the other person that got my 10K was originaly in 13F and also checked
via AA from LAS.
The other person didn't want to give back my original 10K.
I didn't argue at all because I was asked by the manager to move to F...
(not 13F but F=First)

I have the same route in 2 weeks. Lets hope it happens again

LiorM