Planefags, help me out!

I just saw a big prop plane fly pretty low over my house. I didn't recognize it at all and thought it looked weird, so I rushed in and pulled up radarbox. Nothing anywhere close on radar. It was big, low flying, 4 prop plane. Had to be private cargo plane or military. It was in NW Louisiana, flying north towards Ark. By the time I Capcha probably 10 min. ago. AF base not far so its normal to see military planes, but how often do you guys see planes IRL that aren't on public radar?