Assuming that Sanae relocated to Gensokyo around Summer 2007... there barely would have been one iPhone model at that time. People were still using iPods!
It is considered her commemorative day because of the pun with "Hifuu Club" and the fact that today's birth flower is the violet!
The pun:
Hifuu club → hifuu kurabu → hifuu ku(rabu) → hi(1) fu(2) ku(9).
About the birth flower:
Sumireko's name contains the same kanji as the one used for the violet (菫). Apparently the type of violet that happens to be the birth flower of the 29th of January is the sweet violet.Sanae-san, unable to wrap her head around the generational gapWe're no longer in the Heisei era? Po**mon is planning to launch its 10th generation? The latest iPhone is the 16th?T... there's no way...huuuuuuuh?"Eyephone"?"Hunterhunter"?Ah~... But Hu*ter x Hunter hasn't reached the Dark Continent yet...