It could have been that, for whatever reason, it didn't include a transaction fee ... in which case it can take forever for the transaction to confirm on the network. The fact that it shows as unconfirmed means that it is not an issue on SR's end, but rather on the end of whatever wallet you are sending from. If you want me to double check on it for you, you can PM me the BTC address you sent them to so I can just check it out on blockchain.info for you.