It does not surprise me that PMG would grade it as such, but then PMG doesn't elaborate on the standards it uses. PMG-25 could mean anything. I could invent a grading company and if you give me $50, I'll call your note AU-50 if you want. As long as I'm not telling you anything about how I arrive at that grade, I'm not doing anything really different from PMG.
Your note may be firm like a Canadian VF+ (or it may not), but technical grade is just one aspect when considering value. Another poster thinks it looks Fine, and that opinion is probably based more on the look of the note than anything else because I'm sure he didn't see the note in person and assess its firmness. So the aesthetic grade is probably lower than the technical grade, and I would agree that the value of the note would be well below the technical grade's catalogue price.