[dddd]

A suddenly-bent wheel with no history of trauma often turns out to be a failing rim, where the eyelet is no longer being fully supported by the surrounding rim walls.
Note that inner and outer walls can fail on double-walled rims, so the failure could be hidden under rim tape.

Look for cracks in the aluminum, both inside and outside of the rim.

The eyelets themselves may also fail, especially when corrosion has been at work, and can be hard to locate without first locating the affected spoke with lost tension.

Sometimes also some harmless settling of mating surfaces can occur and cause a spoke to lose some tension, but this is less common so a tension evaluation and inspection are warranted.

I would at least now mark the location of the affected spoke (the one that best responds to truing tension to correct your current out-of true condition), and keep an eye on that spoke's tension and surrounding structures, including at the hub.