Lately I have had the experience on my Necromancer of newly swapped in utility schools acquiring the current cool down timer of my signets that are cooling at the time. For example:
In combat
Utility bar: Consume Conditions, Blood is Power, Epidemic, Signet of Undeath, Plague
Use Signet of Undeath in combat. Signet goes on cooldown (~120s)
Out of Combat
Switch Blood is Power for Well of Suffering. Well of suffering inherets the cooldown timer of the Signet of Undeath currently cooling down. Someone suggested in another thread regarding Guardian consecrations having a cooldown issue, that the problem may be due to the trait reducing signet cooldowns.
This does not happen in every case of skill swapping, and I have noticed no particular pattern for the behavior.
Thanks