I guess more clarification is appropriate. When allowing the tardy re-wash, a full explanaitoon should be given, and a re-wash is extended as a courtesy... since she did come back. I suppose it all depends on the attitude exhibited.
Besides, we do not know the whole story. We don't really know how the CCG is instituted, what is printed on the receipt, what controls are in place for abuse, etc. Plus there are two fundamental philosophical differences in question. I see it as an opportunity, and you appear to see it as a liability.
How about if her car got dirty the next day when a bird pooped on it... but she was unable to come back due to some personal circumstances. She traveled out of the country on an emergency trip and just returned... or she was bed-ridden... or whatever.
Life's too short to be wasted on the negatives. Enjoy!