Uh-oh, open freezer door...

[Capitan NeMo]

Of course it all depends on the enzyme. Certainly do not toss any enzymes becuase a majority of 
them may be just fine. I had a similar experience and found many  restriction enzymes worked 
just fine after a period of several hours at around 0 degress C. I would simply idicate on the 
tubes that the particular enzyme had a breif period of warmth.

Good Luck

Eric Hanson
University of Umeå, Sweden