The 5D and the color red

I was meeting with a photographer yesterday who has quite a bit of experience and an quite a resume as well. Since we both have shot with the 5D for years a topic came up that I was unaware of... The 5D has dificulty shooting the color red. More accurately, it blows it out. More often than not he has to go into Photoshop and create masks, go to a dupe image and lower the exposure, drop it back in to the image blah blah blah, what a hassle.

Anyone else ever hear of this?