Hello Tfortony,
Welcome to Apple Support Communities. We understand being concerned regarding the red vertical line on your iPad's display, and we'd like to help.
Does this line temporarily appear, or is it permanent on the display? Also, does this seem to occur when using a specific app, or does it occur at random?
To get started, please restart your iPad, and see if the issue persists:
Restart your iPad
Also, make sure your iPad is up-to-date on software. When you navigate to: Settings > General > Software Update do you see any available updates?
If so, please back up your iPad, then update as explained in the following links:
How to back up your iPhone, iPad, and iPod touch
Update your iPhone, iPad, or iPod touch
If the issue persists afterwards, please contact Apple for further assistance.
Get Support
Cheers.