However, let's entertain the possibility of it being other more concerning possibilities. Generally, over-heating is considered a potential neurological problem, but it can also be the common condition 'Carpel Tunnel Syndrome'. This occurs when a tightening of the fibrous bands in the wrist obstruct the hand's nerve supply. A simple reflex test can be performed; tap the underside of the wrist with two fingers. If you feel an electric shock-like effect radiating into your hand then it could be that. A GP or physiotherapist would easily be able to diagnose this.
Another possibility is allergic reaction. This wouldn't be a permanent heat but then there are suggestions that liquid soap contains a chemical that results in a prolonged irritation or burning.
Foods high in sodium (i.e. Salty) can also cause this problem. Drinking more water in the day can counter this, as can cutting down additional salt to food during and after cooking. This lack of fluids in itself can be a factor, so regardless of salt intake - drink more water.
Aside reducing sodium, it could be a deficiency elsewhere. Pantathenic acid (B5) could be lacking, or even Vitamin B12 or Magnesium.
Other less common possibilities include diabetes and, in the case of women, ovulation or perhaps menopause.