Could be this - and I saw a recent thread about this . . .

I was just looking at seat maps for PIT/CDG for next August, and I see that 1A & 1B always appear taken, even 11 months in advance, which, of course, isn't possible. I believe they block 2 seats off for pilot rest, but only 1 pilot will rest at a time. There's some kind of rule, that, if there's even a single unsold BE seat, it HAS TO BE the one next to the Pilot rest seat. I think it was said to be in the pilots' contract - maybe?

So, they WILL sell it - and assign it, but if any one seat in BE isn't sold, it has to be THAT one. (I read here somewhere).

Here it is:

http://www.flyertalk.com/forum/delta...xperience.html

Check post #7 in particular.