Hi and welcome to the forum. It's good to "see" you and we hope you enjoy your visits.
And wow! You've started off with an interesting issue!
Have you tried to fully close the Calendar app, then restarting or rebooting the iPad? To do (apologies if you know):
Fully Close an App (iOS 7): Double tap the Home button (or do a 4-finger swipe up) to reveal a row of icons and cards in the multi-tasking viewer. Swipe up on all the cards until they are all gone.
Then...
Restart: Hold down the power button until the power off slider appears. Slide it off. When the iPad finishes shutting down, hold down the power button again until the Apple logo appears.
If that doesn't help, try this last step...
Reset: Hold both the power and home buttons until the screen goes dark and the Apple logo then appears. Once the logo appears, release the buttons. After a time, your homescreen will appear. Please note that it may take some time for the Apple logo to appear or for your homescreen to appear (or both). This is normal. Eventually, the homescreen will appear.
Hopefully, one of those will sort it. If so, yay! If not, holler back and we'll take another shot at it.
Marilyn