Hey!
This is a bug I too have noticed with the iPhone X, however not with unlocking the phone. I believe I was quitting an application, and the spinning wheel showed up. Shortly after, it quit as normal and I was able to continue using a phone. It's a bug with the software and should be fixed in the next update.
Please make sure to submit this comment to Apple's feedback page.
https://www.apple.com/feedback/iphone.html
Hopefully it will be fixed soon!