Gene is testing the idea that plants grow faster when they are spoken to. He plants five flowers in a pot (pot A) and five identical flowers in an identical pot (pot B). Gene speaks to the flowers in pot A for one hour every day, but not to the flowers in pot B. At the end of his experiment, Gene finds that the flowers in pot A grew faster than those in pot B. This leads him to the conclusion that plants grow faster when they are spoken to. Which of these is an alternative explanation for Gene's results?