In that case, I think one of my players (Florian Moon) gained exp. I only had 2 players at pitiful exp, now I have 3. I counted his minutes, it was 129.6 League minutes, or 293.6 Total minutes (including scrimmage, cup, etc)
One of my players (Freitkenhauer) already has 600 League minutes, 850 total, still no pop. Should be soon though.
Actually, to have a meaningful count, you have to observe the minutes betweens two pops that you have observed, otherwise you don't know the starting experience level of your player.
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."