I know this isn't the iPhone site, but I wondered if anyone else had ever had this problem.
Twice in the last week, I've been doing a fixed distance workout, and somewhere in the middle of it, the iPhone will just announce "Workout Completed", as thought I had hit the end workout button. Once was in a 5K run, and it terminated it after 1.27 miles, and the other I was doing a custom distance workout set at 4 mi, and it terminated it after 3.52 miles.
Of course, when it considers workout completed, it stops recording distance, time, and pace.
Both these times were several seconds after I had clicked the home screen button to get my pace, but I never hit the "End workout" button.
Any clues?