Definitely minor as you didn't drop it or "expose" it to any dangerous stunts!
My guess: 1) Most likely is that one tiny weenie speck of dust may have gotten into the movement and caused it to stop
2) The other would be, the second hand is pressed too deeply onto the dial and this caused much friction to make the movement move freely; this happened to me once, or even dial is not pressed onto the movement properly and hence the second hand has too little space to move properly
Well, in any case, hope you fix your watch up nicely and all the best!