Though I do not have a Gear device, I do have a Fitbit; and sometimes I run into this problem as well. If you swing your arms a lot or work out with your arms in different positions, perhaps your device is recording that movement as steps taken.
Garmin is the most accurate there, even Fitbit trends to over estimate step count. But pay no attention to it, first, it's a matter of 5-10% ahead of real count, and second, just keep improving over your yesterday's score and no problem