Could be. Are the boards for your fence stained or weather treated?

I never got to do either...was gonna just stain the boards with some pretty stuff....the wood was on the back porch waiting for installation....will stain help?

I don't know, but I was thinking it might make the wood taste bad to the bugs. Couldn't hurt if you were going to do it anyway. Best of luck!

If these guys were on the outside of the wood they were not termites. Termites would not be able to exist in the environment outside of the wood. You would also find mud tummels very close by as their means of getting to the wood.

That's not true at all....you're speaking of subterranean termites. They need a moisture source and Drywoods fly to a (potential) source, shed their wings, and crawl around looking for a place to start a colony. I did find out they CAN chew up in redwood just as easily. Although, they're not very good at flying and they don't always succeed at entering the wood. Check this site out, it'll teach you tons:
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7440.html

Another good reason to live in Michigan.

Michigan? Does the sun ever shine there?

Sun. Is that that orange disk in the sky on some days?

Drywoods were probably just setting up shop and you got them before they got to far. Don't worry bout it to much.

Here is a link that might be useful: Pest cemetery