After he fixed the exploit I carried on playing and built the 6.2 BTC up to 12 BTC, then lost it all.

Just as my balance hit zero I got a PM, thanking me for reporting the exploit and saying I could keep whatever I had won using it.

What is it the kids say? fml?

He ended up tipping me 3 BTC which is better than I was expecting. (But worse than the 12 BTC I could have had).