Speaking exclusively with PCWorld, LastPass CEO Joe Siegrist explained how his company came to the conclusion that its servers, which provide cross-platform password storage for millions of customers, may have been . Just one day earlier, LastPass announced that it had noticed a "network traffic anomaly" and was implementing additional security as a result.

Siegrist now says he may have been "too alarmist" in assuming the worst, but that--even if it ended up hurting his company's image--he wanted to act quickly and make sure everyone was informed. Given the proximity of the event to hack, after all, security was certainly high on many users' minds.

I chatted with Siegrist for about half an hour Thursday afternoon. The following is an edited version of our conversation.

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PCWorld: What exactly happened that made you think something was amiss?