I have not read any comments to indicate that they were making any system changes.
There is mention on the Hickory trunked page on RadioReference that they were considering going to "Open Sky." The report was from the beginning of 2009. I looked over the news releases on both the Harris and the City of Hickory websites, and found no mention of a radio change.
Just in case, a common programming error with EDACS systems is not entering the frequencies according to their LCN (logical channel number) assignments. Usually, that means programming a particular frequency in a specific memory channel or system channel, or forgetting to enter the LCN next to the frequency.
( Note the small numbers next to the "system frequencies" in the Radio Reference database ... they are the LCN numbers for those frequencies )