Hard to explain

Lauren
So I had this odd sensation. Idk if it's normal. My first was a c section on February 2014. We are pregnant again with baby number 2. I'm 12 weeks. 
So we just ate a big meal and I was sitting on the couch. I go for a big Breath and a big stretch. I suddenly feel like something ( ab muscle, tendon, idk) moved over and created a uncomfortable stretching sensation mid abdomen.  
Is this normal? Has anyone else felt this? Should I be worried?