I second that - Almost the exact same thing happened to me last week! I had cramping that wouldn't go away and I ended up in L&D for a few hours being monitored. I wasn't dilated at all, but they did detect some mild contractions. They pumped me with saline and sent me home. I'm convinced it was dehydration, and I've upped my water intake to more than 140 oz/day (around 4 liters or a little over a gallon), which seems to be helping. Yikes!
Happily muddled mom to baby Kiki, 11/2010