My Verizon one did the same as well. I ordered a 3 pack of Mr Shield from Amazon, so I loved the Verizon one and put it on. Still has a lift, but less. Verizon seemed to have about 1/8" lift from edges, the Mr Shield is about 1/16", but it doesn't fully cover the display either. It appears the 3 has more of a curved edge than the Pixel 2 had. These OEMs are starting to tick me off.
I doubt it'll be very long before the lifted edges will start to work their way inwards. I had this problem with the Pixel 2, it would typically take a couple months before I started to see bubbles underneath, but I fear it will be worse on the Pixel 3. Arrgh!