I guess you are right - I have my sync frequency (Tools | Options | Synchronization) set to "Every 15 minutes", and I caught it quickly enough that it hadn't happened yet.
Just for future reference, should I have closed Evernote Desktop to prevent syncing once I realized my note content had disappeared, or would that have triggered an automatic sync?
I presume the latter, but just want to be sure in case it ever happens again.
Thanks.