Presumably the two pictures are of the same spider? From the first photo I'd say it was probably a young false widow (Steatoda sp.), because I can see a light band around the front of the abdomen. But the second photo confuses me a little because it looks darker and has a shape more like a money spider, for example.
Yes, if you find a spider of any age it's unlikely that it's the only one of that species around. But Steatoda bipunctata isn't anything to worry about - I see the occasional one in my house. I would throw a nobilis out of the house but not a bipunctata.