On my warrior I’ve observed that switching a skill to a signet while you have a banner on your skillbar in cooldown may cause the signet to inherit the cooldown of the banner.
Example: Dolyak Signet equipped in slot 7, Banner of Discipline in slot 9. Once I get out of combat, while the banner is still at (45 s) cooldown, I switch slot 7 to Signet of Might, and the signet immediately appears with a cooldown sincronized to that of the banner (45 s as well).
I’m not sure every signet and/or banner is vulnerable to the bug; so far I’ve observed that both Signet of Might and Dolyak Signet can “inherit” the cooldown, and both Banner of Discipline and Banner of Strength can “transmit” it.
Note that even with these combination of skills the bug doesn’t always occur, but it’s a pretty frequent (and annoying) problem.
Details of character that experienced the bug: warrior, norn, female, lvl 80.
Relevant traits equipped: no banner-related traits equipped at the moment.
Places where the bug was observed: mostly Ascalonian Catacombs.
The search function of the forum does not seem to work properly at the moment, so I wasn’t able to fully verify if this issue had already been posted; sorry for any inconvenience I might have caused.