A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 102,617
Don't DL's T&C still say that they're entitled to make equipment changes and that aircraft type isn't guaranteed?
Depending on when OP purchased the ticket, I wonder whether there could be some confusion from when DL changed their marketing (cabin names) and fare classes for premium cabin with IIRC domestic FC now being called business class (to avoid domestic FC confusion with D1, etc.).