Hmmm, thats quite a strange set of occurences. It could very well have been ich, though there are a small set of alternate diseases it could also be. The fact it has not affected your WCM & CPD is a stranger part of the dilemma. If it were my tank, I would let sleeping dogs lie and wait out a good couple of months and watch the tank carefully for any signs of a reoccurance. Ich can not live for very extended periods without a host, so they should eventually die off and the tank should once again be 'clear'. Trying to treat might comprimise and threaten your shrimp population as high temps and Ich treatment are not what I'd call 'shrimp safe'. After a month or two you should be fine.
"In the land of the blind, the one-eyed man is king" Desiderius Erasmus