Yeah, my cat does the same thing and has off and on for most of her life, 12 years. She's not sick, but the last few years my friend has noticed that she has gained a few pounds (like going from 9# to 11#). So, I've kinda figured out two things could be going on (aside from the seasonal change when she sheds and DOES get hair balls).
#1 She is lonesome, lonely, looking for something to do and finds her food bowl and instantly finds something to do, but then she is stuffed, and starts to hack until she throws up and then starts to try to clean it up.
#2 She is bored and eats when she is not really hungry, thus overfilling her stomach. My friend had to put her cats on measured amounts of food because they were overeating. Heck, I never measured, I just kept her bowl full. Now, I fill it in the morning and she has to make due until bedtime, and there seems to be alot less throw up.
At any rate, she is very happy, friendly and healthy so I guess is more annoying to me than it is to her. I have just noticed less if I don't offer as much food. (She just came in here and sat looking at me typing, trying to get my attention, and when I didn't stop to talk and play, she went into the kitchen and started munching away. I guess they are not much different than we are!) <img src="/images/graemlins/wink.gif" alt="" />
Trish