Buy a piss test at CVS and see if it comes up positive

I've never taken CBD oil, but I know that orally administered THC in general is less likely to show up on drug tests. The detection limits on all tests are also set conservatively high to avoid false positives, which means trace amounts of THC in your specimens aren't going to make you fail.

I would say you have nothing to worry about. For peace of mind, I'll second chapoid's suggestion to buy your own drug tests. You can buy packs of THC urine test strips online for less than a dollar each. I used them one time to find out how long it took me to piss "clean" after I stopped vaping weed every day (it was around 2 weeks).