Hi @laserjet25
I am somewhat familiar with the relationship between Google and uBreakiFix and I can say that you should have received an OEM replacement screen installed with OEM adhesive. All Pixel repairs should have a '''90-day warranty''' so this problem could likely be fixed for free at any uBreakiFix location.
As for the cause, there are several possibilities such as a small type of frame damage that was missed or a simple defective screen assembly. Either way, I hope that you are able to get a warranty replacement screen.
Best of luck!