They start at about 4-5w and continue every 20 minutes throughout your pregnancy... so having them now is not unusual! They usually aren't too noticable until your last month, according to my books, but they are there.

Fi, I love your ticker, and I'm like you - running across roads, picking lots of stuff up, doing lots of cleaning and whatnot (although not participating in any major sports!) so I'm wondering when they're going to start and stay put now!