Conversations with my daughter...

Hub called home a couple of night ago to check in. This is the conversation between him and LF...
 LF: (I handed her the phone to answer when I saw it was Hub calling) Hi Daddy!!!
 Hub: Hey babe what's up?
 LF:  Mommy's not here. Gram and Pop are watching us, Mommy is at the store.
 Hub:  Oh are you having fun? 
 Me in the background:  What?  I'm here! I wish I was at the store but at least give me the credit.
 Hub and I laughed at this for a while. But then panic set in and I started to wonder...should I just laugh it off as I have a silly, little 4 yo, should I do some reprimanding for making up a false story, or should I be nervous that at such a tender age she is already concocting lies about whom is in the house without even a second thought.