The rider had noticed that one spoke in his front wheel was so loose it hit the computer pickup on every revolution. Fortunately he did not pull it out sideways and then twist it around an adjacent spoke. Riders who do that often make the repair significantly more complicated and expensive than it would have been if they'd found a less drastic way to secure it while they made their way home.
What the rider did not notice was the similarly wobbly condition of the rear wheel. It's behind him, after all.
I had to check and adjust the tension in both wheels. Simple enough. But the spokes are in pairs.