Update on this one, my brewing partner said the airlock stopped blurping on day 5, he checked the SG on day 5, 6 & 7 steady at 1.016. He dry hopped on day 7 and the airlock started going again. Just got a message from him that today, day 8, the SG is down to 1.013 and still fermenting although slowly. Any thought on why the ferm. stopped for 3 days then started again when dry hops were added?