I experience exactly the same symptoms as you do, Rosie.
I also feel rise in my heart beat for about an hour during night.
I don't know what it means, but I guess it happens because it is a hard job for your body to digest all that oil. So it probably mobilizes all its energies and starts to pump blood faster to be able to provide all what is necessary to sertain organs.
I don't think it is salts, cause the syptoms would recure after two morning doses of the salts.