Yes, greys get lighter as they age. I've had 4 greys and the change each of them has made in color is astounding. My oldest mare being totally white now except for a bit of grey on her legs, she also has "flea bites", little red spots. Another one, a filly I raised, was born black and is now dappled grey, a colt that was born sorrel is now a dark dappled, after being a steel grey for the first 5 years of his life. I have a 4 year old grey filly that was also born sorrel and but is still a steely grey. Funny things, grey horses. LOL