I assume this isn't intended behavior. If you pick up a silk bag your Carry limit is *set* to 30. This means that if you had a carry limit above 30 it reduces it. This can be reproduced easily on any save that 2 or more silk bags spawn by grabbing the first silk bag, then leaving the other silk bag to be picked up after receiving the +3 carry limit level bonus. You'll go to 33 from leveling then the bag drops you back to 30.