I can report the same results as Apollo. In a game with braino and his guest (the
D08 Door Blocking Test), I was consistently able to produce the SuperTri while the other two guys were consistently not seeing it.
We'd completely reload District 04, and nobody could see it. Then we'd all travel together to the D04 Supply Cache and return. Voila! I could see it and they couldn't.
Brain figured it was due to the guest he had logged in on his 360. Others have noted that some glyphs do not appear in split-screen mode.
While we were leaving I was killed by the brute (legendary) and when I respawned... it was there.
I believe Apollo mentioned he had seen this as well... or was it Anonymous? Someone else did. I'll test this.
I also want to answer the question: are any glyphs bumpable? Either way, the answer is pretty telling.