At this point I would not be concerned with compaction or clay. I would be concerned with proper drainage. So they pulled out lots of soil and did not remove it??? Is that right? Did this change your drainage? The correct answer is, "yes," but the issue is whether it created a problem for you. It likely did if you are now getting wet soil. Does water collect in one or more areas and not drain?

Did a landscaper spread the soil or was it done by the excavator? Generally I would trust a landscaper to do this job right. And generally I would expect an excavator to simply follow directions to save money by not removing the excess soil.

How often do you water, or have you begun watering yet? And how long do you water when you do?