I think one question you did not address:

how much growth was on the hay when the lime was applied?

I would presume very little, but I don't want to presume anything.  So,  that might be a question you want to respond to.

My gut feeling is that with 3 inches rain, the lime should definitely be washed off. 

If the hay was only 4 inches or less when lime was applied, I would respond in the same way.

So, to restate my question... how much growth was on the hay when lime was applied?