Red lines before crashing

While typing, my iphone 5c randomly froze up, glitched, and red lines and red patches appeared on the screen before crashing. It started up normally and my phone is acting fine so far. Can this just be a software issue? There hasn't been any damage done to the phone and I recently updated to ios 9.0.2. If it's an important detail, I will also add that my phone was not connected to power when this happened.