Thanks Stalizer for the close-up. This may be one-off as you say. There is similar, termed 'confetti flaw' but three/four times larger in size on a recess printed Ceylon stamp; again one off.
This stamp was printed in two operations and the vignette was printed first and then the frame. It is at the first print run of the vignette that possibly a confetti was on the paper and it received the ink and subsequently fell off. Also possible there was an air bubble that did not allow the ink to go into the recesses at the time of inking and was burst on the doctor blade's wipe.
Shermae's pronouncement "is not a flaw", made me think he owned it! cNA