I recently filled my zippo lighter with fuel (non pressurised, don't know what it was, but it was the right type for the lighter.) I put it in my trouser pocket, and now have what feels like a burn on my thigh, but no blisters, just an ugly purple patch. What could this be and what do I do with it? Many thanks. I'm 38, 6'0" 12 stone, pretty fit, apart from the smoking.