Sometimes it gets stuck on a message like that even though it has actually completed the action. Refresh your Web browser - can you see it as approved now?
Depending on how many emails you have currently using that template, it can sometimes take quite a while to approve because it's updating all the emails using that template.
If this keeps happening I'd love to get some details so I can dig into it. If you had your username, the email template and the time it didn't come back I could file a bug and get it on the list to check out.