You didn't notice them at all??? (if you watched their free, that is.)
I guess the top part of her dress was fitted too tight, or she just has large chest.
But it was definitely way past noticeable.
Considering the tone of their music and the rest of their get-up, I don't believe it was intentional.
Of course, if they knew and didn't mind it at all, then I have nothing more to add to this subject.