Welcome to OCDO!
Regarding South Riding/Aldie, that's Loudoun County, and things should be fine.
However, you can always run into a cop who didn't get the message that OC is legal and not suspicious, or just doesn't like OC. So, always carry your voice-recorder and know both the law on where you can and can't carry, and your rights--4A (Fourth Amendment/search and seizure), 5A (Fifth Amendment right against self-incrimination).
I understand the Sheriff of Loudoun County is on pretty good terms with Ed Levine, one of our moderators, so I'm thinking the area should be pretty tame from a law-enforcement angle, but there is always that one chance you'll meet a deputy who didn't get the message or wants to screw around. Northern VA cops weren't naturally tolerant of OCers--we had to remind them. Part of that was the threat and actuality of carry voice-recorders, knowing the law better than the police, and being willing to fight back with formal written complaints, and showing up at in large numbers at City Council and Board of Supervisor meetings.
So, don't get all relaxed. Stay on your toes a little bit.
Did I mention always carrying a voice-recorder? I can say with great confidence that not one OCer has ever had a police encounter and later said, "Boy, I'm glad I left my voice-recorder at home."