Iphone 7 plus wobble on flat surface

Hi everyone! I really enjoy my new Iphone 7 plus. It's amazing and it's the best smartphone I've ever had. But... there is something that really annoys me. One day, I decided to check my phone for wobble. I put my phone face down (on his screen) on wood table. I press slightly each of the four corners, one by one. All corners were perfect...except the left top corner (not the camera corner, the other one on the top of the phone). Then I tought that my wood table is not perfectly flat and tried it on other wood tables. The results were the same - my top left corner is wobbling. Then I check it on glass surface aaand...the same result - my top left corner is wobbling. I am really annoyed. The wobble is very minimal - you have to focus into it to see it, don't imagine it's like iphone 6 wobble and bend - there is no sense between two types of wobble (iphone 6 had a big wobble). I don't know what to do. I searched in the net for similar posts, but didn't find anything.
More information for my Iphone: It's purchased in Bulgaria from my carrier - Telenor. Brand new, Iphone 7 plus, 128GB, matte black. My Iphone has additional screen protection - full covering 3D tempered glass by Iconflang. Can someone help me with advice or explain me is it normal or not this wobble? Is it caused from curverd tempered glass, which I installed? IThanks!