For example this week Jay Cutler was awarded an extra passing yard went from 299 to 300. Chris Perry also had a reception for 5 yards turned into a rush for 5 yards. Carson Palmer ended up with one less pass attempt and 5 less yards.
Here is the official explanation from MFL:
Every week, a couple of days after all of the games are final and your fantasy scores have been calculated, the Elias Sports Bureau (which is the official statistician for the NFL) reviews all of the games on tape and sometimes issues official stat corrections if needed. For example, one of the most common stat changes is when they award a sack to a defensive player that wasn't originally credited with the sack during the game. This can happen when the wrong player's number was written down as part of the official scoring during the game. Another relatively common example is when a passing play is changed to a rushing play (or vice versa) because after reviewing the tape, they determine that the pass was actually a backwards lateral instead of a forward pass.
Unfortunately, there is neither a clearly defined timeframe in which statistics changes are made, nor a single place to get information on these updates. Once we are made aware of an official change, we work with our stats providers to verify the change and then post them on the Help > Whats New > Official Stat Changes screen for you and your owners to review. Then you can use the For Commissioners > Statistic Changes menu item if you decide to apply them to your league. Check out our Latest Blog Post for additional background and info on official stat changes.
For those of you that want to apply these changes for your league automatically each week, we've also added a new option this year to allow you to do that. Just check the box near the top of the For Commissioners > Statistic Changes screen, and then they will applied each week for you. Note that there is not a set time for them to be reported, but they generally will appear on our site either late Wednesday night or Thursday morning.
In years past you had to let me know of a change and then I would apply it, now that they can do this automatically, that is no longer necessary but it does mean that a really close game could take a day or two longer to become "official" so just keep that in mind.
We already had one game decided by a single passing yard, so I think its important for us to get it right and use accurate stats to determine the outcome of games. At the bottom of this page you can see we have had some nail biters but even with games this close it wold be rare for a stat change to have an impact on a win or a loss, but it could happen
http://www.mflhistory.com/leaguehistory.php?id=13
Basically if your game is still within a point when you wake up on Tuesday keep in mind that isn't official until later on in the week.