How do I fix a knick in my windshield?

Ok, I have a VERY small knick in my windshield. I know it happened today when a rock/pebble hit while driving. It is barely viewable; ie. it is no bigger than the tip of a ball point pen. My main question is could/will this spread? I just had the entire windshield replaced less than 2 months ago because a crack, and I want to know before this spreads if theres anything I can do now. LIke i said, its barely viewable, you have to get right up at it to see it and I can feel it just barely. ANy info/comments would be great. Thanks!