Coffee - 2 secs

Ida puts her coffee into the microwave, as she does every morning, for exactly 2 minutes. When the microwave goes off, she opens the door, but then closes the door again and sets the microwave for 2 more seconds. What good would 2 more seconds be?
Pic credit - Coffee Wave Microwave Coffee maker available on http://www.storeshop.com/coffee-wave.html