Update: SpaceX has set the booster back down on the launch mount and reconnected the "quick disconnect" hoses that fill it with propellant before launch. If they refilled it with propellant they'd be close to launching it again! Presumably they will be draining it instead.

Apparently the rails that catch the booster can translate in and out relative to the "chopstick" arms so the booster can be positioned and rotated to match the launch mount after landing.