Help with odd iMessage alert

On my locked home screen, I received what appeared to be a text message alert that said "tap here to respond". There was no number or name at the top of the apparent text alert and it looked odd. I wasn't really thinking, and I clicked the "message" which unlocked my phone. At that point a big check mark appeared on my screen and the notification went away. I had no new texts or unread texts in my iMessage and I can't find any trace of what that was. I have no shortcuts set up on my phone. I've looked on the Apple forum and it seems that a few people have reported the same thing in the past month or so, but no one seems to know what this is. I'm worried my phone was hacked or something. Does anyone have insight?