Redstone torch and powered rails

I rarely play around with redstone cause its complicated for me, but i just tried making a long rail with just powered rails. i placed a R-torch beside a track and it powered up to 9 rails (including the one beside it). i went on to the same distance of unpowered ones (counted out 9 unpowered) and placed another so it would be about 18 powered rails. i placed another R-torch one block ahead of it, and popped the just laid one. i looked back and all the rails were on, whereas 1 rail should have been unpowered. Curiosity got me, and i continued placing another one, and destroying the previous one. I've gone to idk how many rails (example 50) all powered with just 2 R-torches. one at the beginning, and another 50 rails down. Bug? or intentional?