I have seen this several times , sonetines on purpose for experimenting , the area has a Light leak , I call this a double veg method " the problem is it messes up the cycle of the plant taking the plabt back to day one, the buds however get massive. About the fourth to fifth week turn the lights back to 14 to 16 hours a day, it sends the plant back into veg, then rebloom back to 12 hours light after about 5 days , now it will take abother 2 months as the plant reblooms to finish on a 2 month strain , but the buds will be huge