I sometimes have the envelope icon next to my name on the top row lighted up (rendered filled in yellow) even when clicking on it shows no recent replies. Is this a known bug?
The "psychic envelope" has been a known issue for a long time, but it was recently said to be fixed. If you find the problem reappearing, please report to https://meta.stackexchange.com/questions/61012/any-progress-with-the-envelope-indicator.
The envelope will light up when your favorite is updated too.
(This is a back-end issue, please report to https://meta.stackoverflow.com/ in the future.)