edit: Sorry, further research does answer my question affirmatively.. this is just how it works. With that in mind, does anyone else see an issue here with something like a hard drive failure upon send? How would one reclaim their BTC if this happened? Search for the change address in blockchain, and then how to unlock it? Would it use same private key as the address you originally sent from? I'm curious how others guard against this, and feel confident in thier offline backups if the backups themselves are unaware of change addressees..
With default settings, Bitcoin-Qt wallet pre-generates a queue of addresses that it stores in wallet.dat and doesn't tell you about. Any time you request a new address (or any time the wallet needs a new address for "change" when sending a transaction), it draws from this queue and then generates a new address to add to the queue so that the total number of addresses in the queue is 100. As long as you backup regularly (I'd suggest every time the sum of new receive addresses and sent transactions reaches 25 or so) and keep multiple recent bcakups (I'd suggest the 3 most recent). You should be ok. If the hard drive failure occurs upon send, the address that is being used for the "change" should exist in the queue of all three copies of wallet.dat. When you recover the backup, Bitcoin-Qt will see that the address has bitcoins associated with it and will remove it from the queue of unused addresses and use it as an active address in your wallet.
If you frequently generate a lot of transactions or a lot of receive addresses, you might consider increasing the size of the queue.
