I appologize for the mix up, I could have sworn I saw this posted under dog health. Sorry, musta had too many windows open and got mixed up.

Anyways roundworms are very common in puppies and kittens and frequently get them from their mothers. Do you have other cats in your house? It could be possible for worms to spread that way, although I believe they'd need to be sharing a litterbox for that to happen. If the cat had worms very badly then additional treatments may have been required even with the Revolution which only lasts for 4 weeks anyways.

I'm guessing based on the dates you have to give the worm medicine for Roundworms that it's probably a yellowish liquid, Strongid-T, Pyrantel or something similar. We use that one at work quite frequently and it is very potent stuff so you don't need to use a whole bunch. When my 3 youngest cats were little we gave them some of that wormer, and only had to give just enough to fill the slanted part of the eyedropper! It was such a small amount it couldn't be calculated on that eyedropper. lol But it did the job though.