Had replacement front/rear brake pads and front/rear brake rotors replaced only 4000 miles (7 months) ago. At most recent service, was told that pads were "getting thin" (marked 5/B for all on service sheet) and to watch them.

Only second service with this car, and new to Volvo, but I have a hard time believing any car would need brake service again so soon. A "normal" 20-mile commute each day in rural Pennsylvania with few stops.

Is this possible? normal?

 

No, 4,000 miles is not typical for brake endurance, average is 50,000 or so, and rotors should last at least two brake pad changes. It appears the service tech was not reading the wear correctly.
As a rule never accept any work without an explanation of the work to be done, and if in doubt ask to is see the old parts first.

 

Wow! My wife's 2008 has 102,000 miles on it with the original brake pads. When we had the tires rotated 2 weeks ago I specifically asked them to look at the brakes. He said the pads were great...many more miles to go.
We do a lot of road miles but 100,000+ on factory pads?? WOW.
Yea, 4,000 miles.....maybe those folks you paid 7 months ago took your money.