iPhone clicking wrong place

I was given an iPhone 5s, it had already been restored to factory settings for me. The screen is playing up and clicking in different places from where I am actually clicking. For example I was trying to open a text message but it was registering that I was clicking on the edit button or swiping across the to delete the message. The only way I have found to resolve the issue temporarily is to lock the phone. Is anyone else experiencing this issue and is there a way to fix it? Does this fall under a software problem that apple will replace the phone for? Thanks.