We are "too busy"

In the last two days, both of my children have told us that they are "too busy" to do something.  I'm not sure where this came from, but it's both funny and slightly frustrating at the same time.  Last night, Kiera was "too busy" to eat dinner (is anyone really surprised at that one?).  Today, Liam told Kevin that he was "too busy" to leave for school.  I'm hoping that this isn't a trend...I can see it going badly very quickly!