I'm sure the potholes are reminding him of the roads pitted from rockets.

You can always reassure him, validate his feelings, to help him. "Oh yeah the potholes must remind you of the horrible roads in.... that must make you feel really squirrely. Hopefully the county has this road on their list to fix soon so you won't have that reaction." Or such, you know?

Encourage him to talk to his CO about how hard it is to adjust when back on leave. Many military people think it's weakness to share that information. They need to know it's healthy, and that it helps them be a better soldier (i.e) in the long run..because war can get to them if they don't talk.

Good wishes.