If this is your only symptom, I don’t think that there is cause for concern.  Often, when a person is under stress or very tired, it is possible to feel some tingling in the facial area, around you lips and under your eyes.  This is a normal reaction to some anxiety.  If however, you begin to experience tingling in other areas of your body: your fingers, feet or arms, there may be a problem with your circulation and you should consult with an internist or neurologist.  A friend of mine had some tingling on her lip and in a few days it became a sore.  As it turned out, she had reaction to some medication she was taking for a skin condition.  If you are taking any medications, check with your doctor or pharmacist to see if what you are experiencing is a side-effect?  If you want to, keep a small notation of how often the tingling occurs, the time of day, and for what period of time, this information might prove useful.  This way, if you need to seek medical assistance you will have more information to accurately describe your symptoms for a better consultation.