My wife and I purchased our first home 4 years ago and it was newly built. I noticed the other day that the shingles seem to be slightly lighter than when we first moved in. Do they normally fade over time? You can't really tell that much of a difference if you are looking at them close up, its more noticeable from a distance. I have a feeling they are just taking a beating from the sun during the spring and summer since the house is tall(2 floors) and with it being a new neighborhood the trees are not tall enough to provide any shade.

Yes they do.

You are absolutely right, the sun is the primary reason for the fading.

Wait until you have to fix a leak or something. When you patch with your leftover shingles you will notice it even more. Looks like a quilt. Can you tell I have had this happen to me? :(