Suzuki does seem to spec the use of some VERY soft steel when it comes to their fasteners.
Years ago (another lifetime it seems) I was a maintenance techician in the Air Force. On some sub assemblies, we had single use fasteners. You would torque the fastener to recommended specs then secure with a keeper wire. When it came time for disassembly and inspection, the fastener would be removed, discarded and replaced with a new one. It didn't matter how the bolt looked. We never reused a bolt. A good thing too, since we're talking about mulit-million $$$ aircraft. I can see erring on the side of caution.
I wonder if Suzuki does the same. We're all back-yard wrenchers. I don't know of anyone here who is a Suzuki factory trained technician. I'll bet you that if you were to read the Suzuki maintenance guide, it probably states to replace the cylinder head bolts if the head is removed for any reason.
I know I will. When I swap my cam chain later this summer, I'm going to replace all the bolts in the head. It adds $26.00 onto the job, but knowing I can torque the bolts to proper specs without (reasonable) fear of them snapping is priceless....