Causal Stories

Bill's wife, Sue, is out of town for the weekend. She leaves Bill a message that says, 'I just saw this marvelous bookend. It's called a Bartlett bookend. So pretty! I'm going to go back tomorrow and get one. It will be perfect for the left side of our bookshelf'. Bill goes and visits his friend. Bill and his friend talk for a while, and when Bill asks if his friend is willing to sell the bookend, his friend tells him it's a precious heirloom and he can't part with it. Bill waits until later when his friend is in the bathroom, and slips the bookend into his bag. Finally, Bill leaves his friend's house with the stolen right-side Bartlett bookend in his bag. Then the next day, Sue goes and buys the left-side Bartlett bookend. So, when Sue got home, they had the paired set of bookends.

Did Sue cause them to possess the paired set of bookends?