That's weird. He got back to me quick everytime. There was one time I e-mailed him on a Thursday but didn't get a response until the following Monday but I think that was because of a storm or something.
Just an idea... lets not forget that his emails saying"your zendrive is ready" is known to be in your spam box..So my educated guess would be his general reply emails could do the same..Even if it is a different email as his order one? So check there:BEER