It's nearly impossible to get high from second hand pot smoke, and equally impossible to fail a drug test from it. When inhaled, pot smoke is stripped of nearly all of it's THC, so "second hand" pot smoke has only trace amounts of THC in it. You'd be more likely to fail a drug test from smoking hemp.

So yes, you are fine, and yes, Slaynish is full of shit about getting high just being around people smoking. If anything, it's just a mental high, similar to the placebo effect.