--is called delayed summation; sensations happen not immediately after the stimulus, but some seconds later, and they build out of proportion to the actual strength of the stimulus.

That can be a symptom of a number of things--small-fiber neuropathy of the face, for example, and also of Central or Thalamic pain, in which there is damage to the spinothalmaic sensory tracts, which often happens in cases of stroke, MS, central nervous system infections, combined degeneration form B12 deficiency . . .

Take a look at :

www.centralpain.org