There is honestly NOTHING at all wrong with 80% UNLESS your ambient temps are cold... 78+ and your fine, congratulations you'll never have a bad shed =) and a happy snake!
IF for your sake you want to know, Use this
http://exoticpets.about.com/od/herpr...hygrometer.htm
This will help you to Calibrate your gauge to + or - for proper humidty.
Lastly with stick on ones they are very unreliable as other say Because IF a drip of water from mister or condensation gets near or behind it. Well now the readings will skyrocket to obserd amounts! I just use them for more of a "guidline" having a rack system i have 0 hygrometers and havnt ever needed one, i know my snake room sits at 50% dry times and 60% normally all my snakes have been happy for 2 years now going on 3! i check on them every 1-2 days and if one is in shed, he gets a sticker and my attention(which just means i mist him at night/morning + a small deli with a hole punched lid with water) I have a temp/humidty gauge for my entire snake rooms, and ran with ARS rack so humidity will rougly be the same. As i said I juse use it as a guideline! aslong as your know your humidity isnt extremely low or vis versa you should be fine(/Health wise)! And can judge by his shed!