Mauritius Stamp – "Diagonal Line At Flagstaff Base" Flaw?

I have noticed a distinct diagonal line running to the left from the base of the flagstaff on the highest tower.

I understand that this stamp is quite common, but this particular feature caught my attention. Could this be the known "diagonal line at flagstaff base" flaw/variety, or is it simply a printing irregularity or accidental mark?

I would be grateful for any information about this variety, including whether it is constant, associated with a specific plate position, or listed in any specialised catalogue.

I am attaching a photo of my copy for reference.

Thank you in advance for any help.