Got notified from a new thread not watching at the time

That's because someone posted to your thread but it was from a new person posting their own problem. In other words this new person was hijacking your thread. I moved it out, gave it a title and created its own thread.
 
I'm confused. That person started a new thread. As it shows post #1 in their post & my reply is #2. If it had been in my thread, their post number would be higher. Correct?
 
If it had remained in your thread, yes the post number would have been higher. When I moved it out into its own thread, the system renumbered it to #1 automatically.
 
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