New to humidors, need some help

[Jmallred]

I recently purchased my first humidor and after reading many tutorials, seasoned it properly then let it rest and stabilize before putting any cigars in it. It seems to work very well and has an excellent seal. But the one thing I've noticed is at the top of my humidor, it has one shelf in it, the humidity is 79% then when I move my digital hygrometer under the shelf the humidity is 72%. These numbers have been constant for the whole week Its been in use after the seasoning period. The hudifier is mounted on the lid of the humidor so it is right over top of any cigars I put on the top shelf. So my question is. Is this too much variation? Is 79 too high? Should I get rid of the shelf and keep them all in the bottom or just have a steady schedule of rotation?