Is it exactly 10 seconds every time? This might indicate some sort of ppp error. Or more random?
What do you see in the logs? Does it do this if you setup the connection manually instead of using the script?
Have you set the PPP session to be 'always on' (idle timeout = 0, which is the default setting)
using rc.reload_interfaces seemed a bit crude when I suggested it earlier and it still does. It maybe that it is causing some other undesired consequence. It would be much better to simply reload WAN or indeed just have it redial. Sadly I'm not sufficiently familiar with the code to suggest anything better.
Edit: rc.linkup WAN up (or should that be 'up WAN') perhaps?