I was reading about brain wallets, and saw an example of a private key for a phrase like "password". Just for fun I imported it into my bitcoin-qt wallet, and saw a bunch of new entries (deposits and withdrawls) that took place over the last year. I think my total balance even went up by 1 satoshi.

I forgot about it, but recently have seen a few deposits (and instant withdraws) happen, and it got me thinking: is it dangerous to have this in my wallet?  Would bitcoin-qt ever send change to this address, or does bitcoin-qt ALWAYS use a new address for change?

should I be paranoid and make a new wallet, or is it harmless to have this in there?