Later in the same ride, I recognized the same situation about to occur, and moved out into the middle of my lane, forcing the guy behind to slow down and wait to go around. The first time, I didn't realize it soon enough to claim the lane. Do you take the lane on a two lane road all the time?
Yes. Always take the lane. If conditions warrant it, you can always give more room, but your starting out position should be in the lane. Check out
CommuteOrlando for information about riding in the traffic lane; they have lots of good videos and animations.
And +1 on using a mirror.