I see the same thing a lot on the bow I have that I shoot B-50 on. I can shoot awhile, set the brace, shoot awhile and when finished, unstring. Several days later when I restring the bow, the brace is high again and it takes a few arrows through it to stretch back out to the correct brace height for the bow. I'm one of the guys who does not like to leave a bow strung when not shooting it every day. Just one of the downsides of B-50, but boy does it ever shoot quiet and smooth on my Martin/Howatt!