Fuel Stabilizer made my bike fart...

[Mr Jumper]

I filled up my gas tank and put in some fuel stabilizer.  After running the engine for a little bit I changed my oil and then...

my bike farted from the gas tank, like a tiny trumpet playing.  I opened the gas tank up and it gave off a little puff of gaseous air.  Did this happen because of the fuel stabilizer or something else?

[TheRedOnesAreFaster]

I'd guess that your running of the engine warmed up the gas tank enough that the fuel expanded, thus causing an increase in the air pressure in the tank.  The noise you heard is just the excess pressure bleeding off.