As you say, you can get it for quoting someone's post. Once you reach a certain number (even if it happened months ago) you get muted.
I've had a few undeserved mutes like this. I'm currently on over 6 red banners, so I'm waiting for the next mute... it's inevitable.
I was muted yesterday. I did not know why. I contacted support and learned it was a bot mute based on alleged profanity (a three letter work referring to either one's posterior or to a donkey). The support admin cited two sentences as examples. One, I wrote many months ago and was not allowed to post it. I was warned at the time. The other is still on the site in a post that I was responding to (and foolishly quoting).
The bot needs a tune up.