Yes, repeated bans for the same offense usually carry longer punishments each time. But someone can only report you for something you do.
Are you sure the ban was revoked? On just about every case I hear about, the ban is pardoned, i.e. you are given a second chance and allowed to go back to playing, but the ban stays registered and is taken into account if it happens again.
Sometimes it's a first time for an otherwise good player, or the player truly seems to regret it or have been unaware, or the player is given the benefit of the doubt (like if what was reported could be interpreted in different ways), and Support gives a chance, but it doesn't mean it was a false report.
If your gold selling advertisement wasn't as clear as you make it sound, or if even once in a whisper you didn't mention it, that would give someone enough evidence. For anything that skirts very close to breaking a rule you have to be extra careful. Some people will abuse a badly-written post, but there's no way for GMs to know which is which, so it's on you to make sure to never leave room for someone to exploit it.