Yes. When Strava matches you to a segment, it's likely there won't be an exact match given the GPS data in your activity. This means that your segment match may be slightly longer or shorter than the actual distance covered by the segment. When we calculate average speed on a segment, we use the segment's distance and your measured time on that segment, instead of using the distance you actually traveled. On very short segments, a larger the percentage of the segment's total time is accounted for by the sampling rate of your GPS device. Unfortunately, this is a limitation of our segment matching process at this time. Here's more on how to optimize segment creation to ensure this doesn't happen.