Under golf ball history, on the rest of the history of the Pro-V1, the picture is showing a black number for the V. it would be more consistent that the X came out with red and not black. I also think the Pro 100 was red and the Pro 90 was black.

Here:
www.titleist.com/.../on-the-tee-the-launch-of-the-first-pro-v1-golf-ball

In the old days of the pro trajectory balls the 90 compression had red numbers and the 100 compression had black numbers and Titleist was black. The 80 compression/ladies ball the entire label was red.