In Statistics screen, 'm' represents both minutes and meters, while minutes should be indicated by min. In the following list I've included a list of the statistics that display each one:
Minutes:
Minutes Played
Since Last Death
Sneak Time
Meters:
Distance Walked
Distance Crouched
Distance Sprinted
Distance Swum
Distance Fallen
Distance Climbed
Distance Flown
Distance Dove
Distance by Minecart
Distance by Boat
Distance by Pig
Distance by Horse
Distance by Elytra
Note: To test for this issue, just kill the player. It will reset the 'Since Last Death' stat and you'll be able to see when the 'minutes' mark is reached.
min is the SI recognized unit sign for non-SI units.