Recalling in the enemy base without their vision.

So, my team was chasing this Graves through our jungle. He ran away to the wall of our base and then used his E to go through that barrier (the red laser barrier thingy). We didn't have vision at that time when he used E and when my friend Nasus came close to the top wall, Graves was no where to be seen. So we thought there was no way he juked us since there were like 3 or 4 of us chasing this Graves. He used E and recalled in our base without our vision. I never knew this was possible since we have full vision of the base. Which he did 'juke' us at the end by recalling in that position. Is this 'recalling in the enemy base without their vision' a thing? or a bug? I tested this thing out with my friends and it seemed to work except when the minions are passing by. Somebody please explain this to me. Thank you.