This only happens when mentioning usernames that contain now "illegal" characters that you can't use to make new accounts today. The simple fix is to re add the "s around the name if you edit.
We will not be changing this as we so not support such characters in usernames anymore. Usernames that are free of spaces and special characters are the only ones that will be fully supported.
If you have a old username with illegal characters and are having issues with key site features such as sending fg or posting please pm me and we'll remove the now illegal characters from your name.
Thanks.