Extra km on my Fenix 5x

Today I did a workout of 50km.  The workout was couting down perfectly.  But after 49km230 my watch took a 50km split and 770m further (exactly on 50km) it took a 51km split.  So according to my workout I did 50km, but according to my laps and the total distance I did 51km.  Anyone with the same experience?  On the graphics the distance seems to be correct near the end, but then it jumps from 49km970 to 51km

https://connect.garmin.com/modern/activity/8956572245

On the funny side I ordred the Fenix 7x Sapphire Solar yesterday.  Could it be that my Fenix 5x is jealous-;)?