Demoted Due to Inactivity

Greetings.

I am creating this discussion in regards to a curious message and demotion I received after completion of my fourth game of League tonight. All games were ranked solo / duo queue, and after I had finished the fourth game, which was a loss, I was demoted to Silver III from Silver II due to inactivity. I'm unsure if this is the proper place to post, but this is clearly a bug or glitch, as I play at least 10-15 games consistently per week, for the past couple of months. It was a loss, though I had won one of the four tonight, and had won the previous two from the night before. Is anyone else experiencing such a thing?