It could be a couple of things like either delirium tremens, psychomotor retardation, or pure coincidence. Delirium tremens or (DT's) is a psycho neurological disorder most commonly seen in people that are detoxing or having withdrawal symptoms from chronic alcohol ingestion. DT's are characterized by psychological and motor disturbances like hallucinations, confusion, or involuntary aimless muscular actions. This may surface if an alcoholic goes without a drink for a day or two but his body is accustomed to daily alcohol intake.
Psychomotor retardation can be seen in alcoholics as well as in drug induced states. Alcohol affects the central nervous system, this system controls muscular movements some of which are voluntary purposeful movements but also involuntary bizarre movements. Usually this manifests itself only in the chronic alcoholic that has been consuming alcohol for years.
These actions may also be due to pure coincidence. He may have some underlying neurological disease that is undiagnosed. You notice these movements when he consumes alcohol, but they may be evident when he is not consuming alcohol.