> thinking it possible that the word is not well known in the US. Was this a correct assumption?

I'm not American, but I will jump in and mention that neither 'kerfuffle' nor 'carfuffle' are included in the American Heritage Dict. (www.dictionary.com) - which was a big surprise to me. This seems to indicate that your reservation about using it was not wrong - it is after all a pretty old fashioned word, I think. M-Webster's includes it and suggests it has a Scottish etymology, btw. I also stumbled on a link where people had been writing in to complain about the use of 'kerfuffle' in a newspaper column. The writer pokes fun at the letters:

Gerry Nelson, retired Associated Press reporter, said: "The use of unfamiliar words and gratuitous foreign phrases in the Star Tribune has been a pet peeve for years. The purpose of the newspaper is to transfer information, easily and understandably, from inside the head of the writer to the head of the reader."
"Any impediments to that ('kerfuffle') are stupid and boastful. They exist for only one purpose ('raison d'être'): to flaunt the writer's supposed erudition. Why don't they simply post signs in the newsroom proclaiming, 'I have a master's degree'?

http://www.startribune.com/stories/1519/2921494.html