Not at all, but on the other hand did you really expect the players to read your mind?
No, and this was never really intended to be
the way to do it. In fact, if someone had figured out that it was possible, I would have strictly limited the amount it was usable (with RP of only certain amounts of the peasantry being willing to give up blood or lives to the Light).
But it's the kind of thing that follows logically from the way the publicized mechanics worked—
if you started thinking in IC terms, and not game terms.
Any plot in an RPG, whether BM or table-top, needs to have appropriate plot hooks. If you go to the effort of developing a story element that your players can use, you usually also build in a hook for them to find out about it, assuming you ever expect them to actually be able to use it. You don't (and shouldn't) have to shove this hook in their face, but for the plot to be a good one there has to be a reasonable chance for your players to find it, otherwise what the hell is the point of putting it in there?
This was, IMO, one of the problems with both the third and fourth invasions. Unfortunately, it was a problem in all directions—some hooks were too obvious, others were too subtle, some players were too dense, others too canny.