Refurbished iPhone 5/5C/5S become faded after install. Why?

I'm hoping someone could shed some light on this problem. I currently only use OEM original Apple LCDs from a company that refurbishes the screens. I have been having a problem with all the model iPhone 5/5C/5S refurbished screens. Once in a while I get a screen take looks fine and than after a few mins or when I actually install the screen into the body the picture dulls out. The color becomes faded. Sometimes I've actually seen the color pull from the outer edges to the center. In the past few weeks I feel like this problem has become more frequent. My supplier hasn't heard of this problem before. It's only with the 5's, never the 6's. For example today I did an iPhone 5c. Right after I installed it into the body the color faded. I disconnected everything waited about 30 mins and tried it again and this time (not all the time) it was fine. So I completed the repair. I turned off auto lock and left the phone on all day to make sure it remained okay, which it did until I went to install it into the customer otterbox case. When I peeled off the clear protector sheet off the refurbish screen the color instantly changed to faded. Has anybody experience this before? @jessabethany