Interesting. If I look at the top of the E or the far side of the x then I don't see it. also I think it may be to do with the colour arrangement - two strong colours on a white background, with the eye being drawn to the Ex part, highlighting the arrow.
Smooth - I wouldn't really call it subliminal messaging, just *very* clever graphics design, but that might just be because I equate subliminal messaging to audio/motion-picture stimuli.
Now I know it's there it's something that's going to bug me but be highly entertaining to point out to other people - like how the London 2012 logo is Lisa Simpson giving head...