A/C Fan not working??

I've had my 2008 Touring for about 4,000 miles. I love the car. I just got in it to drive home from work. External temp about 80. Car was hotter than that. A/C set to Auto and 72 degrees. After starting the car, fan did not come on. I cycled power off and on, still no fan. When I adjusted temp higher the display changed appropriately (fan display changed as would have been appropriate for setting) but still no fan. It was as if the car thought the fan was working, but it wasn't. I drove 10 minutes, still no fan. Pulled over, checked fuses, nothing looked blown or loose. Drove another 10 minutes and all of a sudden the fan came on and properly regulated the temperature. Any thoughts as to what might have caused the fan to do this?