Hello and thank you for your question.
What you are describing is most likely a reverse sneeze. A reverse sneeze if an involuntary spasm, and is caused by minor irritation to the soft palate.
This is not normally a problem and less it begins happening all the time does not usually require veterinary treatment.Here is a great site that also has videos of reverse sneezing to be sure this is what you are seeing.
http://www.petplace.com/dogs/reverse-sneezing-in-dogs/page1.aspx
When this happens you can try a few things to help stop the spasm. Rub the throat during the episode to help the soft palate fall back into place.
You can also try placing you finger on her tongue to cause her to swallow, this will normally reset the soft palate allowing it to fall back in place.
If this continues or becomes more often you may want to have her seen buy your vet to rule out sinus infection or a foreign body such as a blade of grass stuck in the soft palate area.
I hope this has been helpful, please feel free to reply back if I can be of further assistance.
Candy
Veterinary Technician
Practicing Veterinary Technician for 23 years. Veterinary Practice Owner, Technician Trainer