Run another tank or two through it then lean out the low speed needle 1/8 of a turn at a time until it is corrected. It sounds a little fat to me. Most engines are like that from the factory.

I disagree with your LHS. If an engine runs like that, especially an AX series, it is either out of tune or has something else wrong. My .46's, .55's and my .75 all run excellent throughout their RPM range.