Problems with the LCD? Negative affect when phone is tilited?

I just recently replaced my iphone 4 screen which is not the first time. I have done this repair many times with very few problems I could not solve. After the repair I began to use the phone and something seemed off with the display immediately. When you tilted the phone to the right or up even a little bit up, the colors would invert as if i had turned on invert colors. It was like an illusion. I even put the invert colors setting on and then tilted it and guess what? It would invert the colors back to the original. Its really nothing drastic because the phone is fully functional but I would like to know what could be causing it? Maybe some damage to the LCD port? Any way comment if you need a better explanation because I know this post must be confusing.