Condensation in secondary?

Has anyone ever experienced this?

Yep! I have seen it before. I used to worry that it was some sort of 'precursor' to mold growth but not anymore. As long as you have a good seal, you should be fine.

Yes, I see it pretty frequently. Presently I have about 12 carboys in various stages of conditioning, and a few of them are showing condensation.

It's nothing to worry about. Moisture in the air inside the carboy will condense on a cool surface, so perhaps the humidity in the carboy did so at some point when the outside air was significantly cooler.

Once it's on the inside of the glass, it doesn't seem in any hurry to go. I think it takes a decent temperature swing to evaporate it.

Hopefully a brewer with a better science background than me will tell us how it all works.

cool. Yea now that I think of it I feel like I have seen this before. I was just checking some that I had going last night and 2 had none, 1 had a little, and the last had a good bit more. Interesting. The beer science experiment continues!

Happens to me all the time. No big.