While the compression of the blanket is totally allowed and encouraged, storing your blanket in the stuff sack for long periods of time can decrease the loft of the insulation and cause the blanket to be less warm. Definitely make sure the blanket is dry and wiped clean before packing it away and periodically take the blanket out of the stuff sack to give it that breath of fresh air it deserves.  This will help maintain loft and prevent odor build up. 

Of course, we hope you're using your Original Puffy blanket so much that it doesn't even see the inside of its stuff sack!