Concrete decking issue

Perpetual summer

Silver Supporter
Feb 17, 2017
Here's the back story, last October we had a pool installed with stamped concrete decking. Contractor sealed a few days after pouring. Fast forward to today.( We have had a mild winter in regard to snow and deep freeze temps.) I was out looking around today and noticed a roundish spot about 8 in diameter and the edges are lifted and crumbling. If I tap on it with my finger nail it sounds hollow. In my opinion it seems ready to pop off the slab. I definitely will call the contractor Monday. Are any members somewhat familiar with concrete or experienced with this issue? Is the contractor responsible? Is it a defect? I find it hard to believe there would be a fix to seemlessly blend with the rest of the slab. It's a two color stamping, which would make it somewhat easier I guess. Haven't really had the chance to use it yet........