Why does Rin have cat-ears?

Question

In the Little Busters!-anime, Rin sometime has cat-ears for a very short time (mostly only a split second). Is it used to show a character trait? What does it mean?

Here's an image of it:

Answer 1

Seems to be the Sprouting ears trope.

A symptom of a Super-Deformed Art Shift, where occasionally a character will sprout Unusual Ears or other animal features (paws, tails, etc.) during certain moments to accentuate certain aspects of their personality. What ears symbolize what varies from culture to culture, but generally they break down into three groups:

1. Cats: Genkiness, excitability, occasionally irritation. Usually accompanied by a Cat Smile.
2. Dogs: Hyperness, clumsiness, affection. Generally done to a character who is loving, but not all there in the head.
3. Foxes: Mischief, wisdom, slyness. May be either friendly or malevolent.

Another form it might be used (did not watch little busters so not sure its the case) is when the character hears something special hes not supposed to know. This is often used to show that they have heard this secret information.