BI missed some unreported travel?

When my military recruiter was filling out my SF86, he left out some of the information that I provided for foreign travel. He said that it wasn't on my passport and so it would be better since an extensive travel history could be a red flag for my TS application. He nevertheless put my passport number down on the SF86 and told me to just lie. It's been two years now and I have been working with my TS clearance virtually everyday without issues. I am wondering it could be that the investigators missed this. All they did was check the stamps on my passport. Couldn't they just look up CBP records to verify?