What happened is that your pace should really be just below 4:00, but rounded to 4:00. The minutes are rounded correctly to the next integer, but the seconds are rounded up to the next integer which really should be 00. It is a new function and Garmin missed this corner case.
Then you come to a results page. Scroll down to see how to contact Garmin. If you don't see any way to contact them on that page you need to click one of the buttons with categories to get to a new page. Scroll down and look again.
