Postpartum drug screen?

Is it even a thing? Please no judgement. I use cannabis and quit the entire duration of my pregnancy immediately upon finding out I was pregnant. I obviously tested negative at delivery but my DR knew about my usage prior to pregnancy as i was open about it. I'm obviously wondering if it's safe to start smoking occasionally again, obviously not without my husband being home and with me to help care for my child when I am smoking. Is postpartum testing at my 6 week checkup even a possibility? I'm in CA and they claimed at delivery that they test everyone during that time. I dont believe I was tested any other time during my pregnancy as my records dont indicate it and I only took one urine test in the very beginning which I dont believe was drug tested.

Edit: to those asking if it's legal, yes it is but they still test you and can involve cps during pregnancy which is one reason I would never smoke pregnant