Twin pregnancy question

Hey ladies so I wanted to ask you guys before calling my OB because I don’t know if I should be worried or not

I’m 27 weeks

So I’m carrying twins and I notice yesterday that when they stretch out it’s like they are pressing down and putting pressure because I can feel it it’s not cramping because it goes away after they stretch out.. idk if it’s normal because they are getting big but it’s the first time experiencing it...

I just wanted to make sure I’m not calling my OB if there’s nothing to worry about