Time remaining difference

[《LarisaCzech》]

Is there any reason that there seems to be a difference between the time remaining on the left page of the bomb list (with the list of friends times/all times) and on one of the bombs themselves? I found that on one of my best times, I had the time off by one millisecond on the left page of the bomb list (in the minutes:seconds:millisecond format) compared to the bomb (seconds:milliseconds format). The time on the bomb was one millisecond less than the page said afterwards, which I found strange, since I just assumed it would take the bomb time and just use that.
I know it is a small difference, but it just makes me curious, since I did not see it happen on any other bomb (it is also possible that I just did not notice it happen), so the only idea is rounding up the time being different for both of these parts of the game.

Thanks for any reply/idea!

(I am open to clarifying anything that is needed. I hope my post is understandable, but I get if I worded things in a confusing way or something)