I truly hope in a strange way that it is indeed something spirit-like. Otherwise, it may have sadly come from a gas station patron that had a bad day at work, and then they consumed Taco Bell food much too fast for supper, etc. The customer dispersed his/her gastric discomfort before getting back into their vehicle again. Ever heard the slang expression "float an air biscuit?" hehehehehe maybe methane gas can be blue in high concentrations?????