Hi! You know, to give you the best answer, I think I should ask you a few questions first that will help define the problem and the situation.
That you are asking this question implies quite strongly that you believe there is some importance in this behavior on her part. By itself it would not necessarily mean something very suggestive of anything serious. So I'm wondering:
Do you have a concern about your wife that you think this behavior is tied into?
What is that concern? Can you share as much as you can about it?
Any extra information that will help, feel free to share.