A reference that may be of interest to you is Perkin Elmer's newsletter
(Amplifications, May 1990, Issue 4). There is an article called "DNA
generated by PCR (...) has non-template nucleotide additions: Implications
for cloning PCR products. They suggest using Klenow to remove the extra
nucleotide (which probably is an A). Hope this is of some help to you.
wallen at csc.fi (Internet)
wallen at finfun (EARN/Bitnet)