If the 3711 hadn't finished (and it seems it didn't), then you just racked off all the higher attenuating cells (still in suspension) and left all the low attenuating cells in the cake.
In essence by racking before the beer finished, you are selecting the lower attenuating yeast cells for your next beer. The result could be your next beer does not attenuate as much as you want it to.
This is why they do not recommend re-using yeast more than a few times, because every time you brew/ferment, you are preferentially selecting certain characteristics of the yeast (by temperature, by when you take it, buy the OG, by how long it is in the beer, and by any of the many other variables that go into a beer).