One minute video loop = 15 seconds?

I'll ask the collective board wisdom to see if someone else has experienced this.

I tested my K2 at 1080 @ 30 fps for 1-minute loops (to keep file transfer fast). I got 1-minute clips for the entire trip and people had some criticism as to the image quality. They suggested I repeat the test at 720 @ 60 fps and compare results.

Did so and came back with video clips not exceeding 15 seconds and of only a few minutes of the trip. I was communicating with the K2 via the iPhone app before starting and after finishing.

Any idea what's causing this? Thanks in advance for any help you can give.