Doh!

While in Lutsen, offspring #2 asks me, "Should I change into different jeans?  These have a spot from Grandma's." 

In a perplexed, quiet, concerned and almost care taking voice I respond (seriously worried about her laundry skills), "You don't have any grandma's anymore and haven't for over a year."

She says with a spark, "Grandma's in Duluth!  Where we had lunch yesterday?"

Doh!