"Oh, uh, I'm okay! Um...I just wanted to uh, see how everything was!"

Not to mention that with how nervous she was feeling she thought she would delay going back to her own apartment. Just for a little bit. However, she starts to feel more awkward than anxious when she sees how tired he looks, especially since she was just dropping in unannounced like this.

"I-If this is a bad time, I can come back tomorrow or uh, some other time or something...!"