RDWHAHB...It's just CO2.
I've had the same experience multiple times from both my own carboys, as well as when over eagerly smelling the wonderful smells coming off of the blow off bucket at commercial breweries!
Packaged: A bunch of random stuff...*and* American Pale Mosaic SMaSH
Recent Meads: Mead Day '11 Ginger Metheglin, Mead Day '12 Traditional (orange blossom) Mead, Fresh Simple Cyser '12
Primary: Hopefully being refilled next week!
Secondary: Why do I keep this line here...?
Bulk Aging: Cocobochet
Planned: Hop Metheglin #3 (NZ hops), Trad. Gesho T'ej