Elder Boss platform Glitch?

So Im solo-ing and about to fight the Elder. I start first by building a small stare case up one of the pillars just a little past the top point so I can use it as an archery platform. I summon it and run up to my platform only to realize that I, by complete coincidence built it on the pillar that he summons RIGHT BEHIND. The result was when he summoned instead of moving he kind of just sat there staring at me in place for about 2 minutes while I opened fire. Then he moved slightly closer to the right, but still just sitting right next to my platform staring at me. This continues for about 4 minutes while i'm just firing away. Finally he starts summoning vines only to realize i'm too high up for them to hit me. Towards the end of the "fight", his vines occasionally started to grow out of the platform I built, but only one part of it so I just had to move up and down a little on the stairs to avoid them. It ended pretty quickly after that. Im guessing that his hit box or pathing, got caught on the platform I accidentally put in the way?? Either way I feel like I cheesed my self big time because I beat him with his face a couple inches away from mine the whole time, my feet never touching the ground and taking about 15 damage total. (His arm when he slams it down to summon vines just ghosts through you if you're at level with his face btw). This ever happen to any one else before??