Is it normal for an electric hot-water heater to drip?

I justed moved into a new apartment where I have an electric hot-water heater. While the apartment was vacant (for over a month), the power (and water heater) were turned off. At the base of the heater where it connects to the piping there is a small knob, and a hole to access and see the connection. When I started the power, the heater started dripping at the connection into the pipe connected below (just visible from the access hole). If I turned the knob, the dripping regulated into a steady stream. Since it drips directly into the pipe, I was wondering if this was normal? or maybe just because it was heating?

The power in the apartment was only on for about 2 hours before I had to turn it off again. During this time, there was constant dripping.

Is this normal? if not, is there something I can do myself to stop it, or should I call a plumber?