First brew (all grain). Seems everything went fine during mash and wort. OG was 1047. Pitched a packet of wyeast 1056 at 65 degrees. Maintained temp at 66. Had lag time of about 20 hours. Started decent active fermentation and remained for about only 18 hours. Now I have no action on the airlock. I peeked in the bucket to find about 5-6 inches of krausen. Obviously I'm going to let it ride for another 6-8 days before I move it to secondary, but I'm concerned about only 18 hours of active airlock. Teach me, oh wise ones.