No need to call Rome. While arguably grosser than light-shaded shoulders, this too is normal for our fascinating breed.
What you are seeing is the “third eyelid” – formally called the nictitating membrane. If you look in the mirror, you can see the human version of this membrane, which is non-functional: It’s that pink lump in the corner of your eye nearest your nose.
In a normal, healthy dog, this membrane is never visible when he is alert and active. However, during particularly restless, twitchy periods of sleep, the dog may open his eyes partially, and this membrane may be visible covering a portion of the eye.