Painting - Please help with touch ups!

I did something extremely stupid. I moved into a town house that has the entire house 1 color. After moving, there were several scuffs on the walls. Rather than wash them off, I decide to use paint. The paint that the owners left was what the house was painted with (4 years ago). I shook the can and mixed the paint, then touched up the scuffs with a small brush. When they were dry, I didn't like the little blotches, so I got out a roller and made rectangular sections. The new paint is slightly darker than the walls now! Is this because of ultraviolet light fading the walls over the last few years? When viewed from certain angles, it's definitely noticeable. Should I either (a) leave the new paint alone and hope it eventually fades to match or (b) repaint the entire walls to match. Please help! Any suggestions would be much appreciated. Thanks!

buffs, Most of the time wall paint gets paints get darker with age or as they turn from gas heat, cooking and smoke. I doubt there will be changes in time that will let you get by with this problem.....Mike