strange "crank" damage

I was out last night when on the way back i heard a strange noise coming from my uni.After changing my pedals over and the same noise still there i took the crank off, Nearly missing the problem when i saw the washer was funny, it looked like someone had got a knife and gone round it and left a curlly bit like butter get me?
any one else had this?
(o and i am crap @ explaining so if i need some more detail ask)

Are you sure that pattern was not on the washer when it was new? Cotterless crank nuts have a “ridged” pattern on the underside that’s supposed to help keep them from loosening. This cuts into the softer aluminum of alloy cranks, and makes a bit of a mess if you change the cranks much.

Nope i have splined cranks,what it was was something to do with the fact i had to long bolts so my cranks kept coming loose.When i got the replacments it milled them i filed them down they are final now.
B4 picture