Have a tab set-up to show hero events. This will let you know when any GMs are spawned. If you do and still don't see any messages about GMs, guess you are just unlucky.
Last night was crazy on Virtue. There were near simultaneous zombie invasions in two zones and shortly after that a Rikti invasion in Steel, a Paladin construction in KR, a Troll Rave in Skyway, and at least one other thing I'm forgetting.
I wish I'd taken a screen shot of my chat window - it was like all hell was breaking loose at once.
(Sometimes, I wish there could be a Dev thumbs up button for quality posts, because you pretty much nailed it.) -- Ghost Falcon
Suddenly over the lasty couple days, the only GMs I can find on freedom are sally and Krakken.
Usually there are more than this! Even the Octopus is strangely absent. I have looks several times through the last 2 days.