Factory prep? Perhaps. Bad paint formulation? Possible. Incorrectly applied? Possible. Inappropriate or poor undercoat/primer, or surface activation, or plating or etc.? Who knows. Coatings are a science, but an endlessly complicated one; there are dozens of things that can go right, and thousands that can go wrong.
Which is to say, it is possible to do everything right, and still not have a perfect result. Hardly grounds for a warranty claim, for example -- if they released product that was grossly and obviously out of compliance with their production standards, yeah, but if they've already done their best effort, I mean, what are you going to expect anyway, at best you just get the thing replaced with an exactly identical product that has the same spread of tolerances. And not saying you're looking for a warranty claim or any legal remedy, that was already mentioned earlier in this thread anyway, just to say, for things
along those lines, what kind of legal sort of basis, if say one wanted to press the issue and if it were still in scope.
I don't see where frame corrosion will ever cause functional breakdown, until it's so visually apparent that you're literally seeing light through it.
A perspective that you may find useful. Steels are often rated in terms of -- wait, we went over this before, with your allthread question, didn't we? -- Material loss rate as a result of corrosion, say in terms of mm/yr, or /decade, under specified conditions. Clearly, the corrosion rate is currently low; if the bubbling gets thicker, the affected area wider, the paint starts flaking off wholesale -- those are warning signs to monitor. Until then, don't sweat it, keep it clean, oh and waxed, wax probably helps here too -- and consider major servicing as mentioned if it gets structurally concerning.
Tim