They're probably just Braxton hicks since you're only 30 weeks. I didn't know what they felt like for a while I think they just ask to make sure you're not in pain. I would think it's a good thing you don't feel them :p if they didn't explain the monitor to you look at the bottom half of it and you can watch it to kinda learn when and what they feel like
Or they could be showing up and you not feeling them. My doctor asked the same thing and then pointed out I'd been having regular contractions fairly close together and I wasn't even aware that's what it was