It's always possible that a bad batch of fuel got out. I have been running Nitro for a long time and I have seen bad fuel come out from pretty much every brand. Do any of you remember the bad Sidewinder a few years ago? Unfortunately it is mixed by either people who can make mistakes or machines that are monitored by people who can make mistakes. The factories are not going to recall or check which ones may be tainted. Its cheaper to pay for an engine here and there if somone can prove it and raises a big enough stink!