I hadn't flatted in almost 2000 miles on a set of Ultra Gatorskins, until Saturday morning. The first flat occurred in the parking lot waiting for the Bike to Battle Cancer ride to start. That one was a teensy piece of glass. Fixed it just in time to start with the rest of the pack. The second one occurred around mile 18 or 20 and it was a small thorn. And of course I'd already used my spare tube. Continentus was with me though and just as I was getting ready to patch it, sag wagon drove by and gave me a tube. Filled it and off to finish the ride. So last night it was low again (CO2 effect) I let all the way down and pumped it back up to 100 and VOILA! Flat again. I think the tube failed around the valve stem, the stem was not threaded and was moving around a little bit in the hole. So three in three days. Not bad eh?