When I touch the top corners where the screen starts seems like the lcd is getting distorted patches. Same with the bottom when I touch the corners & home button.

Is this to do with fitting. I have done several before & not had any problem before. I know I have had a problem with pinching the cables. e.t.c. As I have a snug fit or is it just the quality of the replacement lcd. Glass being cheap. I have not overtightened the screws.

Any advice would be helpful. Thanks in advance :)