Less water in bowl-is this normal?

[martha]

I've noticed that the waterl level in the bowl is not as high as it used to be. I've also noticed that my bathroom floor is not as level as it used to be. It now angles back. I used a marble and it rolled back towards the back wall and then I got out the level. Could this cause any problems? I ordered my new Drake, but don't want to have any underlying problems I haven't addressed.
Thanks,
Martha

 

[Terry]

The lower the back of the bowl is, the less water the bowl will hold.
You may need to shim at the back.

Also, make sure the black rubber hose from the fill valve is putting water into the overflow tube.