its normal i have had alot of steam beers that fermented for 2 weeks
the bulk was done in the first few day but it was not over for 2 weeks.
thay will really get going too, a blow off tube or beer glass over the carboy is a must that will blow airlock off left and right
Once, during Prohibition, I was forced to live for days on nothing but food and water. ~ W.C. Fields