Braxton Hicks

Anyone pregnant with Twins or multiples start getting Braxton Hicks at 17 weeks? When I've been up walking for like 15 minutes the top of my belly gets really hard. There's no pain but a lot of pressure making it uncomfortable. It goes away when I lay or sit down and drink water. It's been four years since my singleton pregnancy so I don't really remember if this is what BH feels like. It's too early to go to L&D to be checked out. I also feel like even with twins it's too early for BH. Anyone have any advice or insight?