OK.  False alarm.  I continued to look through Filezilla settings and found that it takes configuration information from putty default account.  I added the key to that account, saved it, and Filezilla works fine now.
However, now I'm somewhat troubled about the admin account.  Previously, I used to be able to log in to admin remotely, and make configuration changes.  Now I can't login to that using putty.
Any suggestions?