Wait, I'm confused....
Did you measure your OG with a COOLED wort sample? If you're taking the sample hot, it will show lower than it "actually" is. Sorry if you already knew that, it's just always good to check.
Also make sure that the gravity you're taking immediately after the mash is y our "boil gravity" this is NOT your OG. Your Boil Gravity will be lower than your OG because of boiloff.
If you already knew this, sorry for wasting your time.