The only thing I'd worry about with a crease would be that it might create a stress point, sort of like when you machine a drive shaft on a car and accidentaly machine in a small groove, or forget to machine a radius where the shaft widens, abrupt changes can create stress points.
I remember this from a metal removal (machining theory) class I took in college, perhaps one of the engineers on the board can elaborate.
Steve

Approach life like you do a yellow light - RUN IT! (Gail T.)