Going to post this here - it turns out AskDifferent is ... pretty dead.
So - weird things today.
Because of another issue, I had to close google chrome and restart it. When it restarted, Pandora started playing - however, there is no pandora to be found. No window nor tab.
I thought I'd be able to figure out where or what was going on with the Activity Monitor - but I found very little to indicate which instance (if any at all) was hiding and playing pandora stations. So, my next step was to run ps aux|grep chrome -i with very little helpful information, just a slew of instances. Figured I'd try running ps aux | grep 'pandora' -i which returned nothing at all.
So - I have an invisible pandora tab playing pandora somewhere. Obviously I could try re-starting chrome, but that's not the point. The concern is that this is even happening at all. Is this a flash issue? Do I need to worry about youtube playing via mysterious phantom chrome instances?
If anyone can help me with this, I would be ever so grateful!