Kitchen Large Electric Appliances - Viking refrigerator shelves splitting

I have a Viking built-in refrigerator and recently the plastic shelves in the door have been dramatically cracking and splitting on their own. When I pulled them out they were stuck pretty tight which leads me to believe the mold that holds the shelves in is shrinking. I talked to Viking, a Viking distributor and the store I purchased it from and nobody had heard of this problem. I can replace the shelves but I'm wondering if this is a symptom of a bigger problem. There is no indication that the unit is going through temperature changes that would cause the interior plastic to expand and shrink. Not sure what's going on. Anyone have any experience with this?