I think it must be to do with other uses of the word.
A dog lead
I lead him away.
A good read.
I read it at work.
Hmmm. Maybe "lead" has more "ee" uses, so the brain sees "lead" and hears "leed"? But then, what about "lead" weights? It was made of lead.
A conundrum wrapped in an enigma...until someone solves it. Don't fight forces, use them R. Buckminster Fuller.