That's not paranoid, that is a very, very smart move to ensure you are not SOL if you need to get somewhere, especially now that loads are high. Old habits die hard, especially if you grew up flying US. At the end of the day, if they announced even a minor delay, you would jump like you would for a VDB voucher and go to an agent (or call) and get rerouted or protected so their union wouldn't screw you. I have definitely been spoiled by DL's reliability - the few issues I have had...well they didn't really end up much of an issue at all.