Color overlay problem

[Crispis]

Experiencing a new issue as of yesterday. If I press the unlock button, there are times when my phone will "partially" display its screen but it has this weird purplish color overlay all over my screen. I just relock/reunlock to correct this problem. As far as I can tell it isn't really affecting anything...Just kinda aggravating. Any ideas what would cause this and how to fix it?