[Tom Line]

If you watch carefully, he begins swinging his right arm to count, but never gets close to the requisite number of seconds for a pin before the other team backs off. They come back in and he begins to count a second time.

I'm not sure why he waved the flag vertically, but there doesn't appear to be a pinning penalty there. Like Tanis said, perhaps they conferred and agreed that the other team backed off far enough, or that you followed them away from the wall and negated the pin.

Rule Quote for further discussion:
An ALLIANCE may not pin an opponent ROBOT for more than five (5) seconds. A ROBOT will be considered pinned until the ROBOTS have separated by at least six (6) ft. The pinning ROBOT(S) must then wait for at least three (3) seconds before attempting to pin the same ROBOT again. Pinning is transitive through other objects.

Violation: TECHNICAL FOUL

If the pinned ROBOT chases the pinning ROBOT upon retreat, the pinning ROBOT will not be penalized per G29, and the pin will be considered complete.