The Fischer catalogue, for Poland, does not seem to show Scott #362 as being forged. While Scott indicates that #341 has counterfeits, Fischer does not seem to provide details, at least with my very limited knowledge of Polish.
If you want more information, visit here:
www.polonus.org . This is the site for the Polonus Polish Philatelic Society, based in Chicago. There is an e-mail address at the bottom of the home page for inquiries.
If you plan to get more into collecting Poland, you might consider joining. The quarterly journal is excellent (I'm a member) and there are some other good references on their web site available for members.