Back in this bike's day Specialized glued carbon tubed bikes did get a reputation for this very issue. The really bad ones would show this after a season or so. The company told us dealers that there had been a bad production batch where the BB shell wasn't properly prepped before assembly, I've seen a couple of these with serious chainstay/shell white deposits. One of the lessons/tasks I would teach the new mechanics was to wipe off the frame and run your fingers over the tube ends, checking for "stuff". There's a reason why the bike industry started to shorten their frame warranties as the frame materials drifted from steel.

IMO this frame has proven that it was constructed better than needed to survive for longer than warrantied. It was pretty close to the leading edge in a production model for it's time coming from a manufacturer (Giant) who was still early in their learning curve.

I would continue to ride the bike and routinely do a frame wipe off and exam. The images don't show the concentration of corrosion right at the joint edge, as in what I saw in the worst cases, that gives me pause. But I also consider this to be the hand writing on the wall. Start the replacement planning and do that when that time is right. Andy