Actually lead pipes are safer than most other options. The lead coating in the pipes keeps contaminants from the pipe itself from leeching into the pipe. Lead is also highly resilent from water errosion. The danger comes from disturbing the pipes either from natural cuases or people physically disturbing the pipes. The lead coating is frail and can easily break off. This exposes the actual pipe and introduces the contaminants you regularly see in tap water.

So single one time testing isn't a good indicator for lead contamination. You would have to test regularly to get a proper glimpse of what's going on with your water.