i suffer from pvcs/pacs but this felt a little different. I was stretching and felt the bottom left ventricle of my heart "quiver"/"spasm" for 1/2 a second. it felt like someone took that small section of my heart and also applied pressure for a 1/2 a second too. anyone else get this :( i'm super anxious 

also earlier in the day, i felt two thuds in that area too. i got a holter monitor (came back normal) two years ago, but i'm always worried.