I'm not sure if I want to see a slap or Shiina immediately backing off on her own next chapter. I mean, the latter is obviously better, but she kinda deserves a slap too. Maybe both...? Yes, I'll go with both. (I doubt we'll actually get a slap though...)
In all seriousness, however, I like how Shiina's insecurities were portrayed here. I agree that this could've been shown even better with more chapters, as someone said above, but the author did a very good job with what room they had, the build-up in this chapter was great.