He also sneezed quite a few times in a row. Last night his hay was a little dusty, as well. I am feeding him a mix of Oxbow and Sherwood (to get him used to it)
If you're getting to the bottom of the bag, the pellets may be more dusty which could lead to sneezing. If there is no discharge I wouldn't be too worried about it.
It could be a dust allergy. But if he eats too fast, get one of those hollow feeding balls for cats that they have to roll to get the pellets out. Be sure to get one that adjusts down to the size needed for rabbit pellets.