That part didn’t surprise me. The stations air system works sort of like a diving rebreather. Yes they recycle the co2 but a little gets lost each cycle, so the

That part didn’t surprise me. The stations air system works sort of like a diving rebreather. Yes they recycle the co2 but a little gets lost each cycle, so they need to add in new o2. That o2 is precisely monitored. Probably they noticed the leak because the stored o2 was depleting faster than expected. As for danger, I know when my scuba tanks are leaking. That doesn’t make me abort the dive as long as the leak is slow and understood. At that point for the astonauts, fatigue was more dangerous than the slow leak.