Could be a number of innocent things. With the humidity and dampness here in Virginia, my boys have had a little sneezing and coughing after having their noses in the grass. They like to lick grass too.
My boys sometimes get hair in their mouths when they lick or chew on themselves, which they do a little when they pick up things in their hair outside.
They also like to eat fuzzies off the floor if I don't vacuum them up fast enough.
If your pup has longer hair, check the corners of her mouth for hair that might be stuck inside her mouth.