We have a mix of elements:
- We get a series of externally observable narrative facts (mostly dialogue).
- We get author commentary on Estela's attitude.
- And instead of being told Rudy's thoughts and feelings via an emotional label or observable behaviour, we go inside his head and experience what he's experiencing—which is a flash of insight and a vision of himself wiping his mouth.
"Why isn't Estela's attitude highlighted as character feeling?"
...then added with kindness...
You could argue that this is Estela's emotion, or Rudy's perception, but I think the best argument is that the narrator is clarifying for the reader how Estela changes her tone so that we don't think she's still being mean.