The sequencer plays back based on a C tonic note. If you want the sequencer to play in the same key you recorded in, first analyze your recorded sequence to determine the tonic. In your case, G is your tonic. G is 7 semitones above C.
Hold down track select, and turn the second soft knob above the screen to turn your G notes into C... ie: Turn it back 7 steps. Now if you look at your sequence, all your Gs will be Cs - and you can play any keyboard note in Gated mode, and it will play your sequence based on that tonic note. ie: if you play the G note, it will play back like you intend.
The alternative to this is just to record your sequences with C as the tonic. But it's pretty quick to just adjust things after using the method above.