Using the glyph of explosive trap (the knockback) makes it even more apparent. Sometimes you'll watch your opponent activate the trap and it doesn't seem to do anything for a few seconds, then all of a sudden out of nowhere it finally knocks them back.
This isn't a latency issue, there is definitely something different since the patch, and I'm not the only hunter noticing this. If I remember correctly, at the beginning of Cata our traps were nerfed in a similar manner and had to be reverted closer to their WotLK arming radius/time. Maybe some code got messed up with them or something? Or were they purposefully nerfed? Either way, it's REALLY frustrating watching people walk over your traps and watching nothing at all happen.