I've been known to make "witty" kind of comments about it to just be able to get a chuckle and move on or at least loosen the "tension" a bit before having to answer any questions (as if there's a lot to really "explain" -- it's a kid...she can read...not sure what else you need to know). Something even like faking surprise MYSELF with the words, "Hey! When did you learn how to do THAT!" or "Well, we've been telling our kids since the day they were born that they'd better be prepared to take care of US someday, so I guess she just decided to get a head-start on a decent job!" or "Her grandparents all claim she takes just after them!" or just whatever sarcastic (though in a "nice" tone) thing pops into my head. I'm a pretty quick-wit just as a part of my own personality, so this comes more natural to me than being, like, HONEST and all of that. :-)
