Yes, polyester shrink in the wash if you are using hot water. It will experience some shrinkage at temperatures of at least 140°F. But it is more prone to shrinkage from 155°F to 175°F.
This means it will only shrink when you are using the hot water setting. Most washers reach between 130°F and 140°F on the hot water setting.
This can cause mild shrinkage in polyester when washing.