If you're buying a single family home in Rockingham County, chances are, you're paying more than assessed value for the house.  Should you be concerned?  No --- it just means that the assessed values aren't currently as close to market value as they are intended to be. 

To check in on the relationship between purchase prices and assessed values, I pulled all single family homes that sold in the past month in Rockingham County that were not bank owned sales.  I then compared each sales price to the assessed value and found that most buyers paid at least 5% more than the assessed value (shown in red above).
 
If almost all buyers were paying significantly less than assessed value, I'd be concerned about you paying more than assessed value --- but assessed values in Rockingham County are still quite low right now, leading to the data above.

For your reference, in these 38 transactions, buyers paid (on average) 15% more than the assessed value of the home.