GA Avg. session duration
You are outputting the average session duration data for GA in minutes with only two decimals such as this:
Converting this decimal to seconds (*60) gives this number:
If you display that as mm:ss you get
Problem is - that is not the correct number - since you only pull/display the minutes with two decimals you don't get the actual number of seconds which is:
Change that to the mm:ss format and you get
Why would you output the number like this? It leads to discrepancy between looking at the GA interface and your numbers - not confidence inducing.