There were a few times like that for me. However, sometimes the presence of spirits around you from a different time will unlock memories of a time gone by. Its not so much a spontaneous regression as it is memories with that person surfacing. I think sometimes it just SEEMS spontaneous.
"The best remedy for those who are afraid, lonely or unhappy is to go outside, somewhere where they can be quiet, alone with the heavens, nature and God. Because only then does one feel that all is as it should be."