Tubaboy, please read this excerpt:
“The Young and the Stressless
Tender, emerging leaves are at the mercy of an often hostile world. Insects wait to feast on them. Sunlight can parboil them. Diseases riddle them until they resemble lacework. One of the ways some plants protect their new leaves is with a healthy dose of anthocyanins. This temporary condition, called juvenile reddening, is usually most intense in leaves exposed to full sunlight. Part of this is because of that natural sunscreen function I mentioned.”
Chalker-Scott, Linda. How Plants Work: The Science Behind the Amazing Things Plants Do (Science for Gardeners) (p. 109). Timber Press. Kindle Edition.