I have commented before that the colour of aloes and echeverias can be altered by controlling the amount of sun and water. Plants like echeveria 'Big Red' need lots of sun to go a good red colour.
While others like aloe purple flush need to be kept overly dry to get the best colour.
Either way colour is something we try to induce in some succulents. Today I was reminded that sometimes colour in succulents is not good and can be a warning of something not being right with the plant.
I had heard about the colour issue before; in relation to offsets. If you take an offset of an agave and it has minimal or no roots, one of the worst things you can do is to put it in the sun. They should be in a nice shady spot while they develop their roots and ability to take in water. Too much sun will turn the plant red in the same way, warning you that it needs to be moved.
It is far better to catch a problem early than to have to nurse the plant back to health once things have got much worse. With problems with the roots, they are difficult to spot, unless you happen to be repotting the plant anyway. So watching out for changes in colour in agaves, is a good one to remember.