iPad "Security Alert" from Apple - legitimate?

Seems a bit scammy. But Safari is definitely locked and won't re-set and can't be used - at least until I tap an "OK" button at the bottom of the screen - something I'm hesitant to do until I know more.

When wife returns to tell me her ID, I'll turn off "Find My Phone" and restore the device to a week-old back-up on her computer.