Facebook isn't a startup; I'm surprised it took 2 days to be honest. This should have been an all-out panic mode, level-1 alarm and push.
Given that at any big company, every change (even a critical security fix!) has to go through review and QA, most startups are probably better equipped to fix this sort of thing than most big companies.
"23rd May 2013 - Reported
28th May 2013 - Acknowledgment of Report
28th May 2013 - Issue Fixed"
5 Days to Acknowledge: Yipes!
In all fairness, it was reported on a major holiday weekend...
Looks more like a 1 day window. Bug was acknowledged on the 28th of May and fixed the same day. This post is almost a month after-the-fact - 26th of June.
A one day window from acknowledgement to correction, but still a five day window from report to correction.