For what it's worth, I agree completely with John 2000--and thanks for the roses. You could go a long time without having a problem. Just be sure you keep (and keep track of) some tiles in case you have a proble later.
One little tip when you try to match grout colors, match a wet color with a wet color. Trying to match a wet color of anything (grout, stain, etc.) to the color when it is dry is almost impossible, so wet what you are trying to match with water or mineral spirits and you will come a lot closer.