The answer lies in the blog; The blogger originally stated:
my initial reaction was “Oh, they are a developing nation and simply haven’t caught up to us yet.”
Then he describes a theory that he formed of why the web designs are like what it is:
Another possibility, however (and my personal theory), is that nurture has trumped nature and Chinese web design preferences are being formed from upbringing and cultural influence rather than prolonged exposure and natural artistic evolution
The commenter, then states that:
but always figured, as you initially did, that their design was just behind
But then, due to the blog, she sees the thing from an entirely different viewpoint, and so she states:
It's nice to see an idea that pops that little bubble of accidental arrogance. Thanks for sharing your thoughts
So, first she thinks, "Oh, Chinese web designs are behind," then she reads the blog, then she changes her mind, so she's like "Oh, it could have been that. That's a new idea to me. That just popped my little bubble of accidental arrogance".
"Accidental Arrogance" meaning [unintended or thoughtless] prejudice towards Chinese web designs.