Haven't logged in since June, suddenly suspended.

Received an email about being suspended until February 22 22:22:22 UTC 2100 (oddly specific?).

I last played on June 19th. Haven't even launched the game since then.

What is the best course of action? I do not like having a stain on my account for something I could not have possibly done. Not sure how I should submit a ticket and under what "category".

Note: I changed my account password upon receiving this email. Yes, it was an official email from Riot Games.