You were not banned for the first grief we found - the one you and I discussed. Later that same day another grief was reported. You took the glowstone and some sandstone from a player's floor and also removed their carpet-tile tabletops.
You have been banned long enough now, considering what a good player you were before you decided to try-out griefing. I really hope you have learned from this and will make sure to be respectful of other player's things from now on.
You will be unbanned now. Please read the rules at /spawn and make sure to follow them.