Hi there!
In the article it is also said that the plane was on a C-check in Manila. If I don't trust a plane then it is definetely after maintenance work has been carried out! Not because the engineers are bad but because errors happen and primary safety items like the mask and its O2-pressure/-flow should be important to us as crew and not just because it would be "illegal" to fly like that A330 did.
Another nice reminder that checking your mask everytime you board a new plane is not such a bad idea
