Was having a conversation with someone. I could see the ellipsis come up right after my message was sent. No message came after a minute so I put my phone down. Checked 30 mins later, ellipsis was still there. Went to sleep and 9 hours later it was still there. I had not received a message and there was no way somebody had that opened for 9 hours. I got a tip to restart my phone so I did and it was gone away. What could have caused this and did I miss a message possibly?