If this only happened once, I would bet that you spilled gas somewhere. If it happens every time, then you have a problem.
A 6' ring of gas is not very much. Gas/oil will generally spread out (and still be visible) at 5 microns thick.
3.24 meters^2 x 5 microns = .00000162 meters^3
Which is equivalent to .05 of an oz. Check the engine for any places where you might have leaking gas or oil. IMHO, a leak is more likely than unburnt fuel out of the exhaust.
Former owner of a 1987 Supra Saltare. Current owner of a Malibu 23LSV.