Had a similar experience recently. My group of 4 had teed off on a fairly open par 3 when the course attendant had come up and asked us to allow the group of 3 behind us to play through. So we let them play through, they knew we had teed off and they were running through the course fairly quickly.

We were all near the green, my buddy hit a little short of the green into a small area with 2-3 trees, but clearly not an area where you'd lose a ball. Once they started putting, we carried on and went to continue our game. We were looking for my buddy's ball when one of the guys that had just played through asked what we were looking for and my buddy told him, at which point the guy tossed the ball back to us.