Holy snap. We're close to the seventh year anniversary of that "whoa". TOOK YOU LONG ENOUGH, MATT!
This is one of the reasons I referred to in the previous comic's commentary for shifting focus back in time. More specifically, I didn't want this scene to take place during their finals (the first week of June), and I definitely wanted Matt to ask her out before the school year ended. I might have other reasons for doing the time warp, but this alone would really be reason enough for it.
For those wondering, Susan has grown to 5'8", or some other number if using the metric system. I'm not that great with conversions, but I think this makes her about 22 meters tall.