Random Vibrations

[Linag1113]

My thunderbolt has been making random vibrations for the last few weeks, and it has been progressing. I read a couple places that it seemed to have been the Groupon app. So I uninstalled it, thinking that might have done the trick. However, the random vibrations continue. No text, no email, no fb notifications, nothing. There are no notifications whatsoever that prompt the vibrations so I'm at a loss as to where its coming from.