Bard Portal transporting people who don't click on it

I play a game the other day, and some enemy players said that they were transported through the portal which they didn't click on; I promptly dismissed them as boosted animals.

However today, the same thing happened to me, and a boosted animal, I am not!

Here is video evidence, as you can see there was never a click on the portal...

I've played with many bards and gone through many portals, I know how they are supposed to work. They aren't supposed to take you in just for walking past them..