I wore a new pair of flats last weekend, and my toes swelled afterwards. Has this happened to anyone else?

So I bought a pair of these http://www.kohls.com/kohlsStore/shoes/brandsforshoes/candies/juniors/PRD~506809/Candies+Gabriella%20Flats.jsp (not the same color, but that's irrelevant) to wear to a band fieldtrip that requires semi-formal clothes. I wore them for about 8 hours to a math competition at a nearby college (so I was sitting a lot of the time, but did do some walking across the campus) to test drive them, see whether I would need to use band-aids on the heels during the fieldtrip, etc. Afterwards, I noticed that my toes had swollen up. Nothing debilitating, but they were definitely swollen and tender. The swelling was gone the next morning. I have bought and worn flats before, and this has never happened. Has anyone had a similar experience, or know what causes this / how to prevent it? I'm reasonably certain that I bought the correct size, and that the swelling was caused by the shoes (no bug bites, and I don't think that I put my feet in anything that would cause a local allergic reaction).