Ugh Czar.....I hear ya. Did you by any chance go in to change your lineup, then at some point click on some player's "NFL News" to see what it said? For some reason, in PnH, when you do that......then 'back' to your lineup......it resets to the last lineup you formally submitted and you have to reenter the changes all over again before you click 'submit'.
Lately I've been bringing up player news in a new tab while I'm on the 'submit lineup' screen so I can avoid making this mistake.

Odd....but this little glitch only happens in a few of my leagues.....not all of them. Leads me to believe it's a piece of code in the particular shell we use at MFL. It's not something commissioners can change or opt out of, etc.
But I can certainly empathize.....I've done it before too.