I'd like to thank all of you for contributing to this discussion. The idiot light illuminated on my tractor at 50 hours, so I changed the oil. When the light continued to blink after starting the engine, I thought something was wrong. Luckily, my dealer set me straight when I called--confirming that the light will continue to blink for two more hours. It's a little disconcerting to have the light continue blinking after changing the oil though. I even tried disconnecting the battery to see if that would reset it and that didn't work.

Thanks again. Time to light a cigar and go mow the lawn.