Sneezing and coughing are uncommon symptoms of Ebola, so that's not super likely.
For whatever matter he may have sneezed to be infectious, he would've had to sneeze/cough (unlikely, unless he had an allergy/cold on top of the ebola) while exhibiting ebola symptoms.
I'm thinking the chances he had allergies/cold that would've made him sneeze, on top of Ebola, all while exhibiting Ebola symptoms considering he's a doctor that's been treating ebola and knew to call himself in are preeeetty slim.