This is an old message, but I thought I would answer anyway. The most important thing with the So Simple cover is how to put it on the baby. There is a wearing guide on the website. If it is put on correctly, it would be very rare to have wicking of any kind. If the wicking was through the PUL, it would be a matter of the PUL being faulty. When the manufacturer poured the PUL on the fabric, it could have developed thin places or cracks. This is very rare, but would be my guess if the wicking went through the PUL. In this case, you should contact the place of purchase.