Thank you for visiting Apple Support Communities.
I see that your iMessage contacts appear out of order. Let's look into this together.
First, make sure your iPhone has been updated to the latest iOS version -- Update the iOS on your iPhone, iPad, or iPod touch - Apple Support
If the issue persists after updating, the following information may help isolate the issue further:
1. Does this happen with multiple iMessage conversations?
2. Do you have Date & Time set to Automatic under Settings > General > Date & Time?
3. Do you see a red exclamation mark or "Not Delivered" alert under any of the messages you send?