My touch screen seems to ghost press the back button and sometimes processes single taps. Is this a talkback issue or a broken phone?

Just bought an LG V30 as my first Android phone, and the touch screen keeps ghosting the "back" function and also seems to still occasionally process single accidental taps to njump onto other screens, particularly in Settings. It's hard to say for sure if I'm accidentally brushing the screen with my palm, etc., or if this is a software bug or hardware malfunction. Anybody else have experience with this happening?