Yeah, ^this^ is basically what I was envisioning for her mission. As mentioned she'll be using the fact that she is pretty frequently around the rooftops as a reason she'd be there at the time, as well as the fact that she knows people in Shuten. It shouldn't be that unusual for her to be there now and again, etc. But I'm totally okay with someone seeing her up on the rooftops before the explosion in some manner.