I could'nt help noticing my yellow coticule looked thicker at one ene and leaned down towards the left so i laped using pencil grid on my dmt which most people use and with in 20 seconds pencil grid was removed so surface must be flat i have repeated this several times but still yellow part on top of slate looks thicker one end and the left hand side looks thinner i have measured and it is acouple of mil out in thickness which is baffaling me i have layed hone on glass and it does'nt rock it sits very firm as any one else noticed this or could it be the blue part that is throwing me out.