Curious Airlock Activity

Now my beer has been in the primary for close to 3 weeks now and I should be bottling it this weekend. Well it hasn't bubbled in the airlock for 2 weeks and I moved it to a spot to bottle ahead of time to give it time for anything shaken up by the move to settle down again.

Here's the weird part. After I moved it the airlock became active again. Probably a bubble every 10 seconds. Now I'm pretty sure its not fermentation close to three weeks, especially after it stopped. What could have caused this? Perhaps trapped Co2 in the trub that was released or something?

You're pretty much spot on. It was CO2 that was trapped in solution. By moving it, you broke some of it free and it blew out through your airlock. Continue your plans to bottle as long as you're at or close to your target FG...

Pretty common....Moving the beer and woosh trapped CO2 or even kickstarting fermentation...either way, it's all good.

I figured that's what it was. I was just interested and wanted to check it with the more experienced brewers. Thanks guys!