I drove the Durham freeway eastbound from 15-501 all the way to I-40 last night, no FIOS billboards. (And they would have been pretty obvious, hardly any billboards there in the first place.)
I didn't notice the billboard when I was driving 147 from Broad St. (though that's not the exit name, darnit, Edit: it's the Swift Ave. exit) back towards I-40 this past weekend, but I forgot to look for it. I definitely saw it a month ago--when I was a passenger going from I-85 towards I-40. I forget exactly where it was....
(And they would have been pretty obvious, hardly any billboards there in the first place.)