Tremors in the hands are typically a withdrawal symptom. It occurs when an alcoholic drinks less than what the body expects. My guess is that during social occasions where you see this happening the person tries to limit the volume he or she is drinking, causing mild withdrawal. As soon as drinking is resumed, these tremors usually disappear.

We saw a lot of "shaking going on" the first 5 days at rehab. After that time, normally, it subsides.