Fortunately the river gods smiled upon me and I was spared. Later, however, that same day my buddy had the same thing happen when his cotter pin fell out and he completely lost his oarlock in the river--forcing me to dust off my mcguiver skills with paracord and ducktape!
Thinking about these two things in retrospect. I solved for them with a bombproof solution. I have a stainless steel sleeve now (with a teflon lining to reduce friction and a ring instead of pin to hold the oarlock. The ring is also outfitted with a fish-shaped anodized aluminum bottle opener to solve another problem when floating.
I later found that most pontoon boats use the same cheap plastic sleeve/cotter pin setup. So my question is how many folks would be interested in a set of these sleves and rings (with fish bottle opener on one ring) if I produced a short run of these for other fisherman?