Sounds to me like you had a case of frostnip, especially if you noted any pallor (paleness) of the skin of your forefoot.
Fifty degree temperature is rather warm to experience this but some folks are physiologically predisposed. I would definitely agree with wearing some type of insulating sock (wool or synthetic) and I would take along a dry pair or two as well as a towel to dry your feet on if necessary, and a change of shoes to put on at the take out.
I would not encourage you to just get used to it. I have seen many people who had repeated episodes of frostnip (who never had full-blown frostbite) develop very severe cold sensitivity as time went on, or later in life.
Full Size Sail Rig
Classic Freestanding Rack
URCHIN Portable Anchor
Electric Kayak Motor
Paddler's Truck Rack
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