Algeria - Fives Trees Instead of Four - 1926-39 Issue

For the Algerian 1926-39 issue showing the Marabout of Sidi Yacoub, Scott's Classic Specialized lists a minor variety as "Five Trees Instead of Four".  But has no illustration of what they mean.

So I went looking on the web and only found an auction listing for a block of four that said it contained the error.  According to Scott's the error occurs in the stamp in position 53. 

Here's a cutout of the photo from the auction site that I "borrowed". 

I'm guessing the left hand stamp contains the error.  It looks like it has an extra blob (tree) to the right of the tree on the left.

Can anyone confirm that what I've circled on the left-hand stamp is the "five trees" error? 

If so, I don't have any!

Thanks!