Good chance what you saw was someone respawning a particular node in the group of nodes, maybe for a rare item, ephemeral nodes, or even the favors from Heavensward.

There are two types of node groups in FFXIV: groups of 4 singular nodes (most nodes in ARR), and groups of 4 paired nodes (most nodes from Heavensward onward). As most DoH know, nodes respawn by you mining other nodes. What many DoH don't know is that you don't need to finish a node to respawn other nodes. In fact, in pairs of nodes, you only need to hit one of the two nodes once to trigger the respawn for another pair of nodes.

As an example case for using this knowledge, you can "focus" on a particular node. Let's say you want to abuse a +1 Gathering Attempt node for whatever reason. You'd gather from the buffed node and ignore its paired node. Then you'd hit ONE node of the next two paired nodes ONCE EACH, which will cause the +1 Gathering Attempt node to respawn. Then you can go and gather from that buff node again and repeat as much as you like. Note that you only need to hit up two of the node pairs to respawn the buffed node; nodes respawn after hitting two other nodes, so you can ignore the fourth entirely if you want.

This is probably what you saw.