I received two separate text messages telling me someone was going to be in a meeting at 10am, as in I am about to go into the meeting. My phone was off and when I switched on the next day, messages shows received time of 6.10pm, appearing that the message was sent after the event.
It is wholly possible that the sender did send it after the event, covering tracks, but could there be a tech reason? All date and time settings on my phone are correct.