Upper Volta Defect?

Was working on some labels for my vario pages tonight, and came to some lovely French colony stamps sent to me a while back by our mutual friend Jeff ILS.
These Upper Volta camels caught my eye. These are 1914-17 Upper Senegal & Niger stamps overprinted for Upper Volta (now Burkina Faso). There happened to be two copies of this 1c stamp, one a little more over inked than the other. I noticed something at the top of the stamp in the arch over the denomination. The curve on the stamp on the left has a dent in it, not present on the other copy.






This collection includes other copies of this stamp, with and without overprints, and this defect doesn't show up anywhere else.

I'm sure it's of no value, it's pretty minor, but do you all think it would be a plate defect or simply some sort of glitch in the printing process?
Just a little fly specking for you.

Cool James. I had one of those a while ago but didn't look closely at it.

These stamps were printed in typography and each color correspond to a different plate.

I think that the defect observed correspond more to a defect in this particular clise than to any occasional impurity on the plate or ink during the printing process.

Checked all mine...nothing similar.
Upper Volta tends to accumulate amongst the WW lots,
so I thought the other day, well I have 200 or so,
I'll mount them and try and complete. Hah!

The average UV stamp on ebay is around $2-$5 add postage / shipping...

Well you can guess the ending, they remain alone and largely unloved.

I wonder whether people actually pay those prices.