I'm doing a ginger beer for the first time. Despite following the instructions on the pack to the letter it took a full two and a half days for gas to start slowly bubbling out of my fermenter, whereas it's usually only taken 12 hours in the past with ales. The contents still look fine and the smell fairly neutral (although it stings the nasal passages a bit if i sniff hard) but i can't help being worried it might be bacteria rather than the yeast doing the fermenting. Should i be worried?