My personal speculation is not glue and I dont think its the answer. I'm thinking it to be the supplier of the touchscreen panel (outermost glass panel of the screen) Chi Mei, TPK or Wintek's parts are giving the tint. Glue itself is applied around the opaque parts (under the white/black frame) of the display panel and how would it be a case where the absolutely transparent plastic has a layer of glue applied which caused the screen to be yellowish?
Also if you were to look at Bloomberg's New iPad teardown at IHS iSuppli video, It is true that glue is not being applied on the transparent part of the touch screen.
http://www.bloomberg.com/video/88611598/
By the way I think you're getting used to the yellowish tint. I think you got an issue.