A few things occur to me, looking at Bubbles' face in the last panel.
1) She's not blushing, something she's quite capable of. That eliminates certain possibilities.
2) Her eyebrows, to me, suggest that she's uncertain how Faye is going to react, and that reaction is important to her.
3) I don't think she's smiling, but there's the potential of a smile there. She's hopeful of a positive reaction - more than hopeful, I'd guess, but still not quite certain.
Jeph has really come a long way in depicting complex emotional states.