Yesterday after sending coins, I checked the transactions in block explorer and saw strange behavior I don't understand. Below is what happened. If anyone understands this I'd really appreciate an explaination.

I have a wallet that only receives coins to a single address. Over time this wallet has accumulated coins from many smaller transactions, but since only one address is used to receive them this one address has grown and has all my coins.

So, as of yesterday: a) the total number of coins in block explorer for that address = b) the number of coins in my wallet.

Yesterday I sent coins for the first time (played a few small rounds of SatoshiDice). I then checked blockexplorer to see the transactions, but the values listed in blockexplorer did not match the BTC sent. Here is what block explorer showed. (Values/addresses provided for example only, not actual)

Transaction 1 - 1 BTC total - 1 BTC sent to 1dice7W2AicHosf5EL3GFDUVga7TgtPFn ( the actual transaction )
Transaction 2 - 1 BTC total - 1 BTC sent to 1dice7W2AicHosf5EL3GFDUVga7TgtPFn ( the actual transaction )
Transaction 3 - 3 BTC total - 1 BTC sent to 1dice7W2AicHosf5EL3GFDUVga7TgtPFn ( the actual transaction )
                                        - 2 BTC sent to [some other address  ] ( extra coins sent, I don't know why )
Transaction 2 - 2 BTC total - 1 BTC sent to 1dice7W2AicHosf5EL3GFDUVga7TgtPFn ( the actual transaction )
                                        - 1 BTC sent to [some other address  ] ( extra coins sent, I don't know why )

After this, I now see the following:
a) Block explorer shows my address as having 3 BTC less than it should (i.e. instead of starting value - 4BTC sent, it has starting value - 7BTC)
b) My bitcoin client transactions do not match block explorer (i.e. the 3rd transaction shows -1BTC in the bitcoin client but -3BTC in block explorer)
c) However, my bitcoin client shows the correct transaction amounts and correct total coins...

My guess is when I sent the coins, instead of just sending coins out to the given address, the bitcoin client created 2 new address for my wallet and sent a random number of coins to those addresses as well. This explains why my wallet in the client still shows the correct number of coins, I'm guessing those new extra addresses are part of my wallet now, it is the only way the numbers add up.

Is this correct? If so why does this happen? Or is something seriously screwed up?

I'm using the standard wallet 0.6.3beta if that helps.

Thanks for any comments/thoughts