So I've been brewing a ton of cider lately.  We have a local apple butter festival and I bought some fresh cider to experiment with.  Ok, first of all, it was labeled pasteurized.  Long story short, I brought it home, left in the pantry for 2 days and now i see activity.. like serious activity.  It looks like I pitched it 4 or 5 days ago at this point.  

I have been wanting to experiment with apple cider vinegar.  So my question to the brewing hive - odds it was contaminated by acetobacter and I can go from here?  Any way to tell?  It hasn't been above ~62 degrees... dangerous?  

Thanks in advance!

Taste it. It's most likely not dangerous unless it's got mold in it. In case of mold I would dump it. Some people would say it's still good, but I never trust mold.

your seeing bubbles? that aint acetobacter my friend. likely a fermentative yeast of some kind.