Are you thin? If so, this is totally normal to see.
Some people can see and feel their heart beat more than others, it isn't an indication of anything, just awareness of the heartbeat. When I lay down and after a minute or so, I can sometimes see my heart beat. If you were nervous or stressed out than that can cause your heart to beat faster and more powerfully (stroke volume increases) and it makes much more obvious. Again, perfectly normal and nothing to be concerned over. ;-)
Completely normal, especially if you are thin. I can see my aorta pulsing at the top of my stomach sometimes when I lay flat.