I've rewatched the episode and the audience laughs when:

- Sheldon yawns
- Sheldon looks forward with a weird expression
- Sheldon is mixing the cereal with the milk and walking

In my opinion, the audience laughs because: of Sheldon faces and expressions, Sheldon is kind of sleepy and grumpy, the fact that Sheldon has some kind of morning routine, the scene is too quiet and they added the laughs.