lager bottling concerns

I made my first lager (Maibock) and it has been lagering at a finish temperature or 30 degrees for about 8 weeks. I've noticed that everytime I open the firdge to take a hydro reading it begins to ferment again. This happens after the fridge door is open for about a minute or so. My hydrometer samples say it is finished fermenting but I don't think that is the case. I'm worried that once I bottle the beer it will obviously be stored warmer and I'll end up with bottle bombs!! Any suggestions?

How are you determining that it begins to ferment again? The only reliable way to know if it is fermenting is if the gravity is till dropping. If you are just seeing some bubbles, that is most likely co2 trapped in solution. If you fermented it at the correct temp of 45-55 degrees and have now lagered it for multiple weeks, it should most certainly be done.

The airlock will bubble with temperature changes, so it's not an indicator of fermentation. If the SG is stable, unchanging after at least a few days, and the beer is clear, it's fine to bottle it.

Thanks guys. You've eased my concerns!