I know, can't tell from this pic, so thought it worth mentioning that it doesn't look like 'Tricolor' to me, from this pic.
There are some close shots of leaves in the plant database here.
Dragon Tree (Dracaena reflexa var. angustifolia 'Tricolor')
Everybody's plant shown there, and in any other venue where I've seen them, pretty much looks the same, with distinct green, white, and pink/red stripes. So difficult to acclimate, I've never gotten any of mine into full sun though. Maybe the extra redness is from that? IDK, just throwing in $0.02' worth of input, I hope, for discussion.
Jmorth, can you decide from being able to see the plant in person? I'd love to see more pics. Never seen one that red until I saw yours, then found that cultivar searching google images for "red Dracaena marginata." What do you think?