3 S (1 S+) in a row?

So umm... i just reached lvl 6 with jinx. and then after that i see that you can get lvl 7 next. So in the next game that i played the day after that i get 3 S in a row? weird and i got mastery 7. i am happy that i got it, but is getting the 3 S and mastery 7 the day after i got mastery 6 luck or coincidence.