What Causes Numbness In Lips Post Esophagogastroduodenoscopy?

On April 2,2015, I had esophagogastroduodenoscopy where a plastic tube was inserted into my mouth to prevent me from biting the tube the doctor used to insert tube. Today my lips are still numb. Should this have passed? I was told that I did a lot of coughing and I assumed that I bit my lips while during so.