Does red pigment always mean too much light?

[dethswatch]

I've got aerial roots on an oncidium that are a few inches long and have red pigment the entire length.

It's under a light but it's rather low light.

Can I take red pigment on roots as an indication that the entire plant (or just the roots) are getting too much light?

Thanks

[estación seca]

Sometimes it's normal. If your plant is growing well it's not a problem.