Maybe. I had UC flare type symptoms for a few months many years ago, my family GI did a sigmoidoscope and said it was just food poisoning so I received no treatment. However, that same GI scoped me a few years later during my "first flare" and said the same thing, then a different doctor performed my colonoscopy and found severe pancolitis. So I don't really trust that I wasn't having a UC flare the first time.
In any case, it was never investigated further because the symptoms went away for a few years when I started the paleo diet -- that's why I had been eating paleo for several years when I was ultimately diagnosed. I'm of the old school and I think going into remission with just diet is "spontaneous," I'm sure others would disagree ;) In any case, it obviously didn't last!
dx'ed UC pancolitis 5/12
past meds: asacol hd, VSL#3, apriso, rowasa, xifaxan, 6mp, cortifoam, pentasa, cimzia, canasa, butyrate, flagyl, cipro, prednisone, remicade, methotrexate, cholestyramine, cortenema
current meds: none!
step one: colectomy, end ileo 1/16/13
step two: j-pouch construction, loop ileo 5/1/13
step three: takedown 7/31/13