Hey there carolb12,
Thanks for reaching out to Apple Support Communities. We understand you’re seeing a red exclamation point on Messages. We understand how this could cause some concern and we’ll be happy to help with this.
If you couldn’t find any messages that failed to send or other issue in Messages, go to Settings > Notifications > Messages and turn off Allow Notifications there. Restart your iPhone after this:
Restart your iPhone
Turn Allow Notifications back on and see if the issue returns.
If it does, check for any updates to iOS and see if this helps:
Update your iPhone, iPad, or iPod touch
You can read more about notifications for Messages here:
Change message notifications on iPhone
We hope this helps.
Take care.