Sneak Peek Results - How Accurate?

So my sister sent my a sneak peek gender results kit and we received our results yesterday. Does anyone have any experience with their results being incorrect? I’m always a “trust but verify” type of person so I’m a little cautious (okay. Maybe a lot cautious lol). I followed all of the collection rules and my husband was nowhere near the house to contaminate the sample. The results came back that we’re having a boy… what are the chances there was contamination and it’s really a girl?