It's funny how your son is seeing those numbers. My mom was seeing them all of the time also. Then I started receiving them too. The first time that I started receiving these numbers was when in June I had a rapture dream. I dreamed that I was being lifted up in the air. When I woke up from that dream I still felt the peace of God surrounding me. I looked over at the clock and it was 4:44am. That is when I realized that this number had something to do with the rapture.
Every now and then I would randomly look at the clock to find 1:44, 1:11, 2:22, 5:55, and etc.
There is this rapture related message board called RITA (Rapture In The Air). One of the member of the board was constantly seeing 1:11 and 11:11 just like your son is. He asked the Lord before he went to bed what the meaning is for seeing all of the 11's. In his dream, a father like figure told him, "You know what it means, it means the ressurection". So now when I start seeing the 11's all of the time, I just thank the Lord and know that soon we will be with Him in Heaven.