It is not clear from your description how long this has been going on but if she feels good and it is only once or twice a day it certainly not cause for alarm. The gagging that you decribe would indicate irritation in the back of the throat or pharynx. That could be due to particles in the environment such as dust, dander or pollen, we also can see that with surface irritants such as carpet treatments or deodorizers. It is safe for you to just see whether this is temporary or whether the pattern is increasing.