Strange

What mail account / service is this, @gmail?
Since you mention sort by date/time, is the date/time value on those "bad" messages in line with how they get sorted?
How do you initially open the message, from the status bar / widget, so you never see it in the message list before it's read?
One thing you can do if this happens is:
Long press the account in the main window (account list)
Choose last item (Diag: message dates)
Choose the Inbox, run the test to completion
When it's fully done, the app will prompt you to email "the developer" (that's me) a log file
Do this, and include the date/time value on the "bad" message - as close as you can (e.g. exact hour / minute values). A screenshot showing the "bad" sorting in the message list would be perfect too.