Malicious files – false positives?

A few days ago I got an email alert from WordFence that said:
Critical Problems:
* File appears to be malicious:
with a list of 63 files (some theme files, some plugin files, including WordFence ones and some core files). I didn’t see the email until a day or 2 later and there were no issues showing in WordFence when I logged into the site. Subsequent scans, including a high sensitivity scan have come up with no malicious files so I am to assume the alert contained false positives that were ‘fixed’ when the next automatic scan was run?