Bronze Border

So today I was played a normal draft game and I was doing pretty well. Towards the end of the game I had 10 kills and still hadn't died and the adc on my team asked me why I was only bronze, had the best stats and they were all gold apparently.

I responded by telling him that he must be mistaken because I have never played a ranked game before due to mid being my only strength. But our jungler said he saw that I had a bronze border too so I was wondering why this would be when I have never played a ranked match before.

I went to my profile after the game and clicked leagues and it still says play ranked to join a league so I'm not in bronze and have no ranked game stats on my profile but apparently people are still seeing me as having a bronze border in the loading screen.

Anyone know why this is? Thanks