Even though its not a problem, but if you want to control it or tame it here's an exercise to try.
It serves two purposes,
1/ it lets you hold back the ring finger so stretching gently stretching the tendon that it shares with the little finger.
2/ it works the little finger in two planes of movement past the normal extension and flexion you would associate with with playing the bass. This gives the little finger a full use of movement it can do rather than the limited movement it gets when fretting. It works on the plucking hand as well.
Hold a cup, glass, or can in your hand not using the little finger.
This means the ring finger is around the bottom of the can, near the base, leaving the little finger free
Gently curl the little finger under the base and touch the pad of the thumb then return it back and stretch it out back as far as it will go in comfort. Repeat about 30 times and rest the repeat again and rest.
What you need to try and do is not just move it under and back from the main knuckle joint, but curl it under and back using all the joints of the fingers to get the benefit.
Whatever you are holding will give the resistance, so if you find it hard to start with use something with a narrower base and work back to a wider one. a standard drinks can is as big as you want to go.
You will feel the tensions not in the finger but in the forearm that is how it should be, any finger pain should not be present so stop if it occurs. The other thing you will find is a tendency to grip the object tighter as you do this, resist this temptation.
This is just the shared functions of the ring finger getting involved.
You may not be able to touch the pad on your thumb, so go as far as you can then back, it will get easier and it will happen.
It is that shared function that causes the little finger to move, and this quick easy exercise will lessen and in most cases stop that happening in a healthy hand.
Remember gently curl the finger under, do not swing it, it is harder than it sounds, but easy once you get it.
