Text Messaging Help needed

I know, I know... this is probably a dumb question, but I'm new at this and would appreciate some help. I have an LG phone and have been text messaging a lot lately. Still not sure how it all works. Here's the question... why do some of my SENT text messages return to my own Inbox? I sent a message, (saved it to my sent file), and after a few minutes, it appeared back in my own inbox, but wasn't in my sent file anymore. Not all of them do this, just once in a while. Does it mean that the person I was sending to has a full inbox and the message was not received? Or does it mean something else? Thanks for answering my newbie question! :-)

I don't really know, I have an LG but don't text much, but did you send the messages to the same person? If so, it would make sense that their inbox was full... I just wanted to say Welcome to the forum!!
Sorry I couldn't answer your question but I am sure someone will be able to answer it very soon!!