Thank you Perf12. I'm enjoying that link quite a bit. Haven't seen a site like it before.
What is my "thinking" here? Well, I'm still something of a novice, and several times on this site I've read that when you think you may have a rarity you should assume that you don't until you can find evidence to the contrary. This present stamp, while perhaps not exactly a rarity, is for me still an uncommon stamp with an uncommon catalogue value. So when I read that for this series, "fakes exist" (in this case, fake cancellations), I assume that's what I've got. Happily, it seems that I may have reason to think otherwise.