Not sure if this is a known issue, or even just an issue with drums of the snake, but...

When logging in while DOTS is in effect and then having it drop (or be released) acts as a debuff to agility.

> Agility : 24 -

It's clear that DOTS is the cause, since recasting at the same mana removes the - and doen't give a +.

>Might you have circled with DOTS up? That's a known bug.

Ah, that is probably it. I did circle today, and must have had DOTS up.