Quite honestly I have never really used AskSage for anything practical.  I have used the macro sage.pl quite a bit and it works great for me.  I don't get the pop up anymore but need to know if it is still there for others.  My plan was to figure out how to insure that it was off but haven't had time to hunt it down.

Regarding terms of service, I'm not convinced that students in general are going to even know that they are in another system and on another machine.  I would think that a student user should never have to see a pop up for anything like that once they are successfully logged into WeBWorK.  Having the ability for the coder to ultimately turn this off therefore is essential IMO.