I can create IR on my 13" rMBP using the checkerboard test, it's not real bold but it's there and it takes a few minutes to fade. However, if I try to duplicate this any other way, no luck. I've tried leaving really contrasty windows open for a long time (10+ mins.), even an open word document with bold text for as long as 20 minutes, then cut to a gray screen and there's no retention. I've tried this multiple ways and multiple times. I don't see it in normal operation either. So what is up with it showing up in that checkerboard test but not being reproducible any other way - any thoughts?