This is no ordinary screencap. This is the very last screencap that you will see of Javert being happy. Of him being blissfully naive. Of him being hopeful because he’s going to have a new job in a new city and is meeting the mayor and everything is good. The very last screencap.
This was right when Valjean denies knowing him, causing him to become confused. And that confused expression basically stays with him for the rest of the movie, mixed with anger, brokenness, denial, a small amount of pity, hurt, envy, cynicism, and pain.
This is the last moment before all of that begins.
Literally the very next screencap is:
And so it begins …
So savor this screencap. Relish the fact that there was a brief moment when Javert was happy.