definitely creepy, but really, it was probably just an excuse to show Iori's boobs. Though if you notice, the 2 different "pictures" have very different bust sizes. Probably to help point out that the pictures are fakes..
This serves as the point to put it into Seto's mind that he's going to come in second to Iori's career. And to realize how much competition he's going to have from other men every single day. I'm really glad that she showed up for graduation, but their relationship could easily go bad fast in this kinda situation, even without Seto's screwy imagination. It's not hard to see Seto becoming more and more doubtful, or misunderstanding things in the near future.