If you go to book it on delta.com, you will see it says "First" class, not business. Perhaps you are confused by the J/C/I/D/Z fare classes. These do not necessarily mean you are in business class. Delta calls it's business class flights Delta One now, everything else is just First. Some systems erroneously just call anything with these fare classes business. I believe most of DL's system will now designate these correctly as First if they are not Delta One routes.

The following flights use J/C/I/D/Z fare classes for First and are neither considered "Business", nor "Delta One". They are just plain old First.

1) Domestic continuation flights of international flights
2) The following JFK trans-con routes -- JFK-SAN/LAS/SEA/PDX/DEN/PHX
3) Flights to the Caribbean, Mexico, Central America, and Northern South America.