I just used an existing address that I could sign from instead of the "sending address" off blockchain.info. Technically, a Bitcoin transaction doesn't really have a sending address. It's just easier to understand it that way.
Please do not do this. The sending address from the TX is what is used to verify the signature.
I may have done this as well... can someone explain to me how to get the sending address, or point me to a thread??

I am looking at the blockchain.info on my TX, but see plenty of addresses, and none saying 'sending address'... I just used an address I knew I could sign with.