Rainbows - Just who are they a sign for?

"And God said 'This is the sign of the covenant which I make between Me and you, and every living creature that is with you, for perpetual generations. I set My rainbow in the cloud, and it shall be for the sign of the covenant between Me and the earth. It shall be, when I bring a cloud over the earth, that the rainbow shall be seen in the cloud; and I will remember My covenant which is between Me and you and every living creature of all flesh; the waters shall never again become a flood to destroy all flesh. The rainbow shall be in the cloud, and I will look on it to remember the everlasting covenant between God and every living creature of all flesh that is on the earth.' " - Genesis 9:12-16

     As I was reading this, it hit me that as much as it sounds this way from the wording of it, the rainbow couldn't really be a reminder to God not to destroy all flesh with a flood again. As if He needed to leave Himself some sort of sticky note:

Hey God,

Don't forget to not flood the 

earth again when you make it 

rain this time.

-God

     Because the thing is, if that were the purpose, the rainbow would appear before the storm, wouldn't it? You put reminders before, not after. No, the purpose of the rainbow it to remind us of God's promise, and to demonstrate that He's already been faithful - if we're around to see the rainbow after the storm, we know He's already remembered and acted according to His promise.
     Have you ever caught yourself being surprised after God was faithful to you? How does it feel to be reminded?
     I know I've caught myself being surprised when I realize God's answered one of my prayers, or when He shows me tender love and mercy when I totally don't deserve it. I feel silly for being surprised =P God is faithful, after all. But as a human I've been taught to believe in (and practice) conditional love. So when I don't behave in a way that deserves a loving, faithful response, I don't really expect it, though sometimes I dare to hope for it. When God acts on my behalf this way, I feel very humbled, thankful, very loved, and very in love with Him. God is good.