My comet was sick!

I think it is from eating too much too fast. One of my greedy little fantails does this every once in a while...some what like a mini-flake explosion and then is fine and keeps on eating. No other abnormal behavior so I've never been worried about it but you've got me thinking about it now. I'm sure someone else has seen this before too.

All my larger goldfish do that.. they gobble up a mouthful of food and then spit some of it out. The smaller fish swoop in then to eat the tiny bits. Seems to be normal feeding behaviour with my fish. Their dining habits aren't very sophisticated.

mine do that on occasion as well. i believe it is quite normal

It's normal behavior for goldfish, but excessive "throwing up" can signal a gill fluke infestation. Check for white bugs in your fish's gills by watching carefully as they breathe and eat. If they're clear, just count it as normal behavior.
This is why I recommend that fishkeepers spend a few minutes each day just watching their fish. When you have a solid idea of the normal behavior patterns for your fish, it's easy to spot something unusual.