A few months ago I had injured myself while
movements in my gym. So, I have thought that this may be a hernia or torn muscle. However, it hasn't hurt me in the gym at all. Also, it only happens, as stated, while lying down (mostly noticed when I wake up in the middle of the night). I would say that over the last 6 months, it may have occured 5-6 times at most.
After being awake and up and moving, the pain dissipates.