open fermenter

I brewed a batch of Rye IPA about 11 days ago. I pitched a 2L starter and had signs of fermentation about 8 hours later. But made the mistake of using an airlock so it got clogged while I was sleeping that night and the lid of my fermenter blew off but I don't know how long my fermenter was open. I woke up around 5am and noticed the lid was off so I immediately removed the airlock, put the lid back on and installed a blow-off tube. Should I be worried that my batch may have gotten contaminated?

I dont think so. Because your airlock blew off, there is some really active fermentation going on, and there will be a heavy layer of CO2 on top of the beer, making it very hard for nasties to take hold. I think some breweries use open fermenters regularly

This episode reviewed open fermenting and some of its self protections, concerns, and effects on the flavor.

http://www.brewingtv.com/episodes/2010/5/17/btv-14.html