kolsch fermentation question

[Stubbs5150]

i brewed a kolsch, fermented at 62 degrees using white labs kolsch/alt yeast for 2 weeks. transferred to secondary and have been cold conditioning at 50 degrees for 3 weeks. today i noticed a bubble or two in the airlock and checked the beer. it is starting to have a slight covering of small bubbles on the top of the beer. as if it is beginning fermenting again. whats going on?
this is my first kolsch and was just getting ready to keg it but i don't want to move it until i have an idea of whats going on.

 

[GilaMinumBeer]

Most likely CO2 coming out of solution.

 

[rocketman768]

It might be fermenting a little again. I have brewed a couple of times with this yeast and noticed that it has a tendency to ferment a little bit on the bottom of the fermenter as well as at the top (in fact, you might notice it STARTS fermenting on the bottom before the krausen forms). I would say it's possible when you racked that you stirred up some of the yeast sitting at the bottom and caused a little more fermentation. This yeast is just a very slow and steady fermenter in my opinion. Don't worry about it though, it'll be just fine.

 

[Stubbs5150]

thanks for the quick responses. i wasn't really worried about it, just curious.