What is this weird lock screen keyboard bug with iPhone 6?

Hi there,

I just got my new iPhone 6 ( not Plus) a few days ago, and upgraded it to the newest IOS 8.3.

I have been encountering this annoying bug where if my phone were in a lock screen mode (doesnt matter if screen is off or on), and I receive an SMS or iMessage message, I get this black keyboard pop up on the screen and it becomes frozen. I would not be able to slide the text message to unlock the phone, nor can I slide the screen to unlock the phone( because the black keyboard is blocking it). But, luckily, I have TouchID enabled, so I could use that at least to unlock the phone each time.

Nevertheless, it is still extremely annoying whenever I get a text message. Why is this happening? Anyone has the same problem?

Thanks

IS

Screenshot of issue: