I called Rogers Technical Support. First person I got wanted me to go through some troubleshooting steps, but as I was using my iPhone to call, she asked me to call back using a different phone.
Second time got through to someone else, he said that they will replace the unit. I was told the new unit will be mailed to me within three weeks, together with instructions on how to return the phone I already have.
I have also found that with my phone, if I place it face down I don't got this problem, it only happens when the phone is laid down face-up.