Yes, it's normal.
When you un-check Resample, you will not make any actual change to your
image. You will only change the size of the PRINTED image.
If you enter new WxH values, your Resolution will adjust to show how many of
your existing pixels will PRINT on each inch of paper.
If you enter a new Resolution, your WxH values change to show the new
(Why, you may ask, am I emphasizing PRINT?)
None of these changes affect how your image is displayed on your screen.
Your screen just displays pixels, and resolution has no affect.
When you check Resample, THEN you're actually making changes to your image -
so take care!
....otherwise, all you're doing is setting up instructions to tell your
printer how to dole out your existing pixels.