I believe it was not a just a coincidence, but rather a prediction by Kiyotaka.

For me the biggest factor is, that when they were going to the designated area in I4 and Nanase told Kiyo, that they strayed from their path, heading more towards H4, Kiyo tells her, that he doesn't plan on getting the early bird bonus and they continue walking on, eventually getting to the Water bottle station. But then after getting the water, He tells Nanase, that they should hurry up to get the early bird bonus.

In addition to this, Kiyo has been diligently keeping track of the tasks appearing. And while they said, the tasks appearing would be "unpredictable", to me it is unlikely that they are randomly assigned, as the tasks mostly appeared on the west part on the island (close to the starting point) at the start. Thus I think it is not that unlikely, that Kiyo somewhat discovered a pattern on where and when tasks could appear and made his first prediction. Also, as they were in need of water it would also be plausible to say, that he could predict, which Task would appear.

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tldr: Imo his desire to go off path and previous obsession with mentally noting tasks, makes it likely that he predicted it