Those who follow the news about Apple products would remember that when iPhone 4 was launched some units had yellow spot in its screen which was not a big issue as Apple had announced it would be don’t in some time.And now just like iPhone 4 , few iPad 2 users have seen the same yellow spot on their screen of iPad 2.And Apple had mention this about this issue.
Apple is using a bonding agent called Organofunctional Silane Z-6011 to bond the layers of glass. Apparently, Apple (or more likely Foxconn) is shipping these products so quickly that the evaporation process is not complete. However, after one or two days of use, especially with the screen on, will complete the evaporation process and the yellow “blotches” will disappear.
So , if have this issue and wondering what to do , so don’t worry and give it some time it would be resolved by itself.Even if it doesn’t resolves itself in some time you have a full year to claim warranty if it’s a serious issue.