Fizzing Beers While Bottling?

I have been making one gallon batches since the beginning of the year and have become addicted to brewing! I have used most of NBs 1 gallon kits and usually follow the same routine; 3 weeks in fermenter, bottle condition for 3 weeks, and everything has turned out great. The last two bottling sessions (Cream Ale and Bavarian Hefeweizen) have presented me something different though. Using an auto siphon and bottle filler, the beer seems extra foamy while filling the bottles. Then when I add the NB Fizz Drops the bottles fizz over and make a mess and I lose close to an inch of beer from the neck of the bottle. Does anyone know what this could be from. I am usually use to a little foam coming out of the bottle when filling it because I use Star San, but I have never had them fizz over when I drop the Fizz Drop in.

What were you’re FGs on the last two? Did you cold crash, then warm them up?

Possible that you have more residual CO2 in suspension on these 2 beers. Which, if using the same amount of priming sugar leads to a possible over carbonation/bottle bomb situation.

The FG of the Hefeweizen was 1.006 and the FG of the Cream Ale was 1.009. I had never brewed the Hefeweizen before, so I thought it was just something different with the beer. But I have done the Cream Ale a few times before, so when I got that different reaction this time I figured something was up. I have never cold crashed my beers, but these were the first beers that I fermented in my basement storage, which stays about 10 degrees Fahrenheit cooler than upstairs where I let the fermenter settle for about 2 hours before bottling.