strange ! vector cut cuts thru 3mm birch ply at 9.7%

[waltfl]

Hi all
the other day I did a vector cut with 9.7% and 40mm on 3mm birch plywood and it did cut all the way thru. usually with the birch ply I need at least 38% and max 8mm.
I don't know what caused this this is very strange .
does anybody else experienced something like this too?
greetings
waltfl