3 occasions smoked marijuana within 90 days, 2 of which were very close to not being within 90 days. Once was about three weeks ago. None were more than a few hits, maybe 1/2 joint of average quality each time . Very good metabolism, no other drugs, very light alcohol use. Any chance I passed a hair test ?

The hair test tests for habitual use. That is like having a joint after work most days. Occasional use, one every month or so, won't come up as positive.

Every time you smoke up, regardless of your health and metabolism and other drug abuses, the THC gets into your blood and is consequently deposited in your growing hair. It grows out and that band in your hair grows out. If you use it a lot then there will be many bands of THC in your hair. If you don't then there will be few. The cut off is designed such that it won't fail a small amount. So if you had three hits, like you suggested, then you should be fine.