Water smells and tastes funny after service.

I took my 3 year old Profitec 600 to get serviced. After getting it back, the water form the group head smells funny, and tastes gross.

The water from the hot water arm as well as the steam wand does not smell or taste bad. So it must be the group head. Maybe it tastes like rubber.

I flushed about 4 liters straight and it is still there. Not as strong as the 1st run, but still strong enough for me.

Is this normal after a service? Did they use a cheap part like a seal or something?