Photoshop History Log Timestamp Cadence Wrong

We are using the Photoshop history log to understand how long a file is worked. The cadence of file actions, along with the timestamps, allows us to calculate the time difference between the last "saved" timestamp and the "opened" timestamp, giving us total time worked. When we import the history log text file into a database and sort by date/time, the perfect cadence is:

• Opened
• Saved
• Closed

However, after sorting by date/time, we are seeing the following cadence on a regular basis:

• Saved
• Opened
• Closed

In the example below, the closed file has been omitted, but you can see the Action: Time column showing the timestamps:

How can a file be saved before being opened?