iPhone 4s ringer button

Whenever I wake iPhone from sleep or if my hand is in a particular position, the ringer window pops on screen and slides to max as if by some sort of electrical current -- the buttons seem to be picking up my touch even though I am not pressing them.  The tiger window then gets stuck on the screen and it Ames siding the ringer setting up and down to fix it.  I have tied a full reset but it seems to be a hardware issue.  Has anyone seen this?  Will a phone cover help?