My 08 corolla 1.8 1ffze recently had an oil change. then on my way out of town the next day

i stopped by the local mechanic with the oddest thing i've ever seen. My
radiator hose was flat as a pancake. It was odd for him too. Anyways he
told me to get a new cap. I forgot. 5 days later i was driving home and all of
a sudden it just died. I had it towed. i mentioned to the mechanic that ive
been putting radiator fluid in it like is was leaking. No leaks in sight. the
mechanic to the head off cause before it died it was making a humming like
noise. he called and said"I don't know how it happened but the pin was
sheared off that rotates the cam. it's not spinning ".What the hell. I'm just
curious. did this have something to do with thatdam oil change?