Apple has silently added another condition under which an iPhone or iPad user has to unlock their device with a passcode, despite having Touch ID enabled, according to a report.

iOS will now ask for a passcode if it hasn't been unlocked that way for six days, and Touch ID hasn't been used in the last eight hours, MacWorld said. A quoted Apple spokesperson claimed the rule has been in place since iOS 9 was released in Sept. 2015, but MacWorld noted this is inconsistent with the iOS Security guide, which only mentioned the change starting May 12. Apple declined to offer an explanation.

The company has several such rules in place, the two most common forcing a passcode unlock if a device is rebooted or hasn't been unlocked for 48 hours. Others require a passcode after new fingers are added to Touch ID, a person tries five unsuccessful Touch ID logins, or someone issues a remote lock via Find My iPhone.

If the discovered rule is genuinely new, it's not clear how or when Apple might have made the change, since iOS 9.3.1 was released in March and 9.3.2 arrived earlier this week.