YC lists about 70 startups, and TechStars about 20. I think with that many companies coincidence is more or less guaranteed -- a sort of weird permutation on the birthday paradox. Or, put another way, there's 1400 "pairs" of startups between these two first, and 3 coincidences. Hardly damning evidence in my book.
Further, the startups in question seem like fairly obvious given the current tech climate. Geolocation is an increasingly big deal these days, as is local, high-quality food. And who doesn't want better comments on their blogs?
Remember: all else being equal, the simplest explanation is probably correct.