I actually didn't get that. I'd turned off passcode in order to let a friend try on the watch and use its features. A short while later, I* got an email saying my Apple Pay credit card had been removed from Apple Watch. I thought it was for fraud-prevention reasons, so I haven't added it back yet.
*I didn't personally, but I'm demonstrating that, even if it is your significant other's device, you don't have to specify it.