New account, 9-1 promos and silver 1? is this a bug?

So I hit lvl 30 , played my 10 provisionals , won 9 out of 10 and got placed in silver 1? I know that ussualy if you have 9 wins you get gold 1+, and with 10 wins platinum, but I got silver 1! Can someone explained what happened? I also had really good scores and got a few pentakills.
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