That would defeat the purpose of Hunter trapping in PVP all together. It's a trap, something that is meant to
TRAP you therefore I would highly doubt that there is any Blizzard event to register to anyone other than the Hunter or Hunter's group that a trap has been placed. Unless of course you're a Rogue and can detect them.
Having a mod to detect what trap was placed, when and where without detect traps would be cheating in my opinion. If Blizzard wanted us to see what traps were being placed we could see them without needing "Detect Traps".