Oklahoma is actually kind of fire prone, and lots of fires are set on purpose for land clearing during spring and fall. Cedars in particular are burned purposefully by land managers because it's a shrubby, invasive species which changes soil chemistry and burning is one of the very few effective removal methods. My guess is that it's a land-management burn done with legal permission from ODAFF and DEQ.

Fires tend to only be on the news if they are close to homes or if they are huge.

BUT... those who are signed up for DEQ's air alerts can get email warnings for heightened air pollution in their county from things like fires: http://www.deq.state.ok.us/AQDnew/AdvisorySignUp.htm (I used to send those out)