Not sure if wards in general set off Teemo shrooms, but pretty sure its just the new dying ward mechanic that sets them off.
Also when I played Teemo on the PBE his shrooms were going off randomly from a different source with no enemies or wards nearby, have not experienced this on LIVE yet, but it is something to also look out for.
The same seems to be happening for nidalee traps though i don't know if it's from wards or the markers that indicate where a ward has been place. It is also not consistent, sometimes it will happen right away as the trap is placed other times it happens after a few minutes.
Can confirm it is on live. An enemy ward dying on top of a teemo shroom causes it to detonate. After it happened to me the first time in game I tested it by putting a shroom directly over where I saw an enemy ward. When the ward died the shroom went off.
This has also happened to me. Whether I kill a ward myself or whether the ward expires, it doesn't matter. My shrooms will go detonated when the ward dies. Very frustrating.
Confirm with Nidalee traps as well
