It definetly could be pre-labor, and more then likely is. But just to let you know pre-labor can take a long long time. With my first it was 4 days of hard contractions every 2 min apart. Though when it continues on like that they usually call it prodromal labor. This time I've been having pre-labor symptoms and contractions since 32 weeks. I finally found a site (though I didn't save it) which listed the differences between early labor, prodromal labor, and plain old braxton hicks. Basically early labor and prodromal labor are the same, just that early labor doesn't last for days (or weeks) and early labor the contractions won't stop at all. But they both eventually get the cervix to dilate to 4 cm and efface. Where as braxton hicks contractions don't do anything to the cervix. Plus it says the difference between a braxton hicks contraction and a do-something-to-the-cervix contraction, is that a bh contraction the uterus gets instantly hard, where as the other contractions are more of a wave type of contraction (usually first felt in the lower back before spreading to the front, though could also be felt as a very strong menstrual cramp). The real key I guess is that it is more like a wave, then instantly hard.
Every woman I think is different though, and experiences early labor differently. And we are not all textbook cases. Just know that whether or not it is early labor, your baby will come eventually.