I think you are giving your Tillandsias a perfect sun/shade combination. The red color could be because of strong light but many varieties will turn red before blooming. Several of mine do just that. As long as you know to bring in the Tillandsias when freezing weather is coming, that's fine. Tillandsia leaves come in all colors and those colors may change with the season, stimulated by heat and light. I have some that will be green while in the greenhouse and they will turn gray when hanging under my oak trees.
Here's one that really turns red several months before blooming. Like many "air-plants", the plant dies after blooming, so you want pups to continue the life of the plant.