Contam. / Condensation in Slants?

So I cooked up a batch of slants a while back and have been collecting and reusing yeast happily for a few months now.

Until I recently had a problem crop up. I store these in the coldest part of the fridge, and up until now have had no issues. I think the fridge had slowly been turned warmer without anyone noticing (or it's just working harder to keep up with the summer).

Suddenly, several batches of slants had both condensation, and new batches of growth along the edges. None of the "blank" slants have ever had any room temperature growth. These suspect slants are all sealed with tape, and this is a problem during refrigeration, well after the initial culture growth and sealing.



Some of the strains fared better than others, but I can't say for sure that any one was immune.

I've now used 1 of these funky looking slants. The beer isn't finished yet, but the starter smelled normal and the samples have all tasted normal. Should I be worried about these others?

As far as I can tell either:
1) The fridge allowed some condensation and yeast growth to take place.
2) Some of these strains got infected, but did not show in the week at room temp, nor at all until suddenly they all did.

and a stupid question: I keep my keezer at 40f ... should I just store the slants in there? or the fridge?

PICTURES:
http://picasaweb.google.com/erykmynn/YeastProblem#

What kind of vials and caps are they? It looks as if they weren't sealed completely.

They are 8 dram glass vials with poly liners in the lids. They aren't the best, but I can't seem to find any others where I don't have to buy $90 worth...

A couple had flaky liners but most seemed fine, they were also completely wrapped with electrical tape on storage...

They were inoculated at different times, but all seemed 'clean' and fine until recently. It seems to have mostly happened at the same time which seems odd.

erykmynn said:

They were inoculated at different times, but all seemed 'clean' and fine until recently. It seems to have mostly happened at the same time which seems odd.

Click to expand...

Did you have a power outage and the fridge warmed up at some point?

I'll occasionally find a slant that looks like that, but usually only the ones that are 1+ years old.