When creating a redstone circuit using target blocks, the direction of the signal is determined by the redstone dust where the signal is sent by the opaque block. However, the shape of the redstone dust is sending a signal to adjacent blocks that should not be receiving a signal. So, to summarize what I'm trying to say, the direction of the signal expected from the apparent direction of redstone and the actual direction of the signal are different under some conditions.
An example of a circuit that exhibits this phenomenon is provided in the attached document.