[delayjoe]

I just came back from two days away from my house and notice the air lock was off of my Octoberfest I brewed on Thursday. Should I be worried that it has been contaminated? It's in my fermenter which is pretty air tight. Air lock has been put back on.

[theDarkSide]

Should be ok, especially if it was during the initial fermentation.  There'd be some much co2 come out that nothing should have fallen in.

[In The Sand]

Two days isn't much to worry about if it was in the initial phase of fermentation (as mentioned).  I had a real vigorous Pliny clone blow the carboy cap and blow off hose off without me noticing for a few days and it turned out great.  Of course it did have half a pound of hops in it so that may have masked any oxidation problems.

[HoosierBrew]

I agree with the above - 2 days, no worries.

[delayjoe]

Thanks, I will find out in October

[brewsumore]

Another reason that I use a blowoff tube at least the first few days of the ferment, and quite often thru the entire ferment.  With the large amount of outgassing of co2 these first 96 hrs, you should be fine.  Otherwise, krauesen reaches and then plugs the airlock, gas builds up, and pop goes the airlock.  At least this is what I'm guessing happened to you.