Not to my knowledge. Happened one time before when half of the league was one lvl higher, rest equal but never for the entire league. Happened to a friend of mine aswell, who was having the same problem a few times. (he's lvl 22)
I think when one is in the top 4, the chance of that person being in a league next season of players with a higher level is bigger. It gotta do with the registration date, can't see any other reason as it's random.