If you did not do anything to warrant a report, such as no harassment/foul language, etc, then it is definitely a false report. Also note anyone that tries to ask for your account in PvP is engaging in reportable behavior.
This happened twice to me too, I finish a match, leave and then a pop up message appears reminding me of foul language (which I didn't even use.)
You can just ignore the report and let KI deal with it. They should be looking into the reports they receive so anyone who makes a false report will have to answer to staff for wasting their time.
Please keep in mind anyone who says, "I can get you to warlord if you give me your account for a day." or anything similar to that should be either reported or warned. I personally try to warn and explain why its a bad thing to ask for such info because if the player is really young they might not understand why its so bad. I personally recommend warning first and explaining over immediately reporting.
On a sarcastic note, yea, doing good in PvP is a bannable offense. How dare you! But on a serious note, it's a false report if you did nothing inappropriate.