There are other factors contributing to changes in post valuation. For example, changes in price of STEEM, and the amount that other people are voting on the network as a whole).
High-dollar-value posts are very susceptible to these changes. If you go to a post that's worth $1,000, and refresh the post a few seconds later, the post value will probably change even if it doesn't have any new votes. Voting on a post also acts as a "refreshing."
Now it is clear! Thank you for your time to help me out with this. Really appreciate it. Tested the refresh of a high payout post. Did as you said.