If it has then you will be locked out from the game. Unsurprisingly this move has left several users rather unhappy. This is because there are many Android users out there who root their phone for other purposes, such as deeper customization on Android, running apps that would not have otherwise been allowed to run, and so on, many of which have nothing to do with Pokemon GO or cheating at all.
This means that this blanket ban has resulted in some unwarranted casualties. In a post on Reddit, it seems that there are various ways that the game will think that your phone is rooted, even if you have folders that are coincidentally named after root-related folders, which will result in the game from not launching.
That being said, there are ways to go about blocking apps from trying to run background processes which will prevent the game from trying to detect root-related files or folders, but your mileage may vary, so this is something to consider if you want to play Pokemon GO on a rooted Android phone.