Power lost in plug-in ports

I noticed last night that my phone wasn't charging when plugged into the port under the dash. I tried the port in the arm rest and it too wasn't supplying power. The USB port did charge, however; so it's a limited issue, but one that will require a service call. At one else discover this problem? My Prius is only two months old...

 

The car was running (yes, I was fiddling with the phone cable while driving. My bad.) I could probably track down the fuse and replace it, but I'm concerned more about why the fuse blew (if in fact that was the issue). There has been no extra power draining device plugged into the ports lately, just an iPod and an iPhone.

 

I tried troubleshooting the problem by swapping out all the components, including the driver. I had a second power adapter and any number of USB to dock connector cables. All the cables resulted in no power. But swapping the dv power adapter did the trick. Both power ports work with another adapter. I'm not sure why the one I was originally using died; it was working, and even now the tiny power light on it glows when plugged into the port—but the power never leaves it via USB. I liked this adapter because it was black, and coupled with a black USB cable was less visible to someone peaking into the car. My working adapter is white, so I may have to use in inside the armrest only.

Thanks to all who offered suggestions.