She didn't say that she was relieved. She just asked him if she's changed. Her facial expression afterwards was a little hard to interpret.
Reasons she could be happy about his response:
1) He's still the Kaname she knows
2) Kaname still considers her to be more or less the Chisaki he knows/likes
Reasons she could be troubled by his response:
1) She still has to worry about his feelings and how to respond to them
Now that I watch the episode again, I feel a little bad for Kaname as well. I think my initial response to view him negatively was because I found him threatening my Tsumugu/Chisaki pairing, even though anime logic dictates that he has no chance. In a way, he's even more good natured and passive than Tsumugu.