Default Strange Touchscreen Issues?

Has anyone else experienced any strange touchscreen issues with this phone?

My phone had a weird "spaz attack" the other day, the same as this: https://www.youtube.com/watch?v=3ZCI0ZISC88

I also find the phone is quite unresponsive to touch at times, especially when texting, as if it can't keep up with my texting.

Any ideas?