Are you really letting people pay with PayPal to send BitCoins to an arbitrary address?
If it's just 1 satoshi for $3 you might be fine (if PayPal doesn't notice), but don't even think of doing that with a more reasonable ratio, since you'll get raped by people cashing out stolen paypal or credit cards using it.
In general, I don't see why you are putting the hash in the address, rather than putting it in a comment in the transaction script, and sending BitCoin back to yourself (or perhaps doing a 0-ouput fee-only transaction, but not sure if that's accepted by clients).
If it's just 1 satoshi for $3 you might be fine (if PayPal doesn't notice), but don't even think of doing that with a more reasonable ratio, since you'll get raped by people cashing out stolen paypal or credit cards using it.
In general, I don't see why you are putting the hash in the address, rather than putting it in a comment in the transaction script, and sending BitCoin back to yourself (or perhaps doing a 0-ouput fee-only transaction, but not sure if that's accepted by clients).