It's called "string tension". I used to have that problem until somebody told me how to fix it. All you have to do is open up the back of your guitar and loosen the bolts that hold the tremelo springs. Don't be afraid to mess with the different parts on your guitar a lot of people are scared to mess with anything on their guitar cause they think they'll mess it up and they won't be able to fix it. If it gets to messed up you can always take it to a music store and get it fixed. But messing with your guitar makes it so that it's comfortable for YOU to play, not the person who put it together.