I don't have any experience with Kentona in amidol, but I did have a similar experience with Kentona and lith printing (yellowing borders and highlights).

Here's a couple of threads to look over
http://www.apug.org/forums/forum37/4...developer.html
http://www.apug.org/forums/forum55/4...tml#post497732 (Read Juan's comment at the bottom of the first page)
http://www.apug.org/forums/forum37/4...m-kentona.html

I know your problem may be a little different, but the solution may be the same.