Jon Skeet got 1505 reputation gain, while the other user got only 1500. How come Jon is not first?
The actual order of users is cached, but the reputation displayed under their name is not. If Jon stays ahead of Silva, then the system will eventually update the list to reorder them. The list usually updates fairly quickly, but you can browse through the list and find quite a few places where there are users "out of order." In fact, this has already updated for me.
There may be a chance that you are getting it from the browser cache. as I have tried the same way and I am getting it in a descending order of reputation.