I have just had my cold water tank in the loft replaced with a new plastic one. About three days after it was fitted a small drip appeared on the pipe that supplies the bath room. Its on the screw join, in the thread between the tank and the pipe.
I called the engineer out and he told me it was nothing to worry about and would fix its self. A week later and the drip is back, the water not the engineer.
I check it every day so it is a very slow leak that amounts to a couple of drips a week. Is this a problem ?
I'd suggest calling whoever installed it and getting them back out there to take that fitting apart, re-seal it, and reassemble it. Do not accept the repair if they smear pipe dope or some other sealant on the outside of the threaded connection without taking it apart...It needs to be taken apart and re-sealed.