Trouble with the mile?

Maybe you were able to get a really good effort out of yourself because of miscounting laps. So Noakes (maybe others) has this theory that he calls the "Central Governor," basically that your unconscious mind will only let you go so fast, because it is afraid that you'll hurt your heart. Maybe you were able to fool your central governor because of the miscounted laps and get an unusually hard effort out of yourself. If this is the case, then you probably just need to run a few more races to get yourself ready for a really good effort.

Of course maybe you just had a couple of bad races.

Don't despair though, if you can do it once then the physical ability is there and you'll probably be able to do it again.

this could be lack of qulity practices, but often when one breaks a barrier or posts a time, it can be mentally tough to dial down and run that time again, especially in close proxmity to the first effort. Although, it could be your race strategy, can you post all your spilts for those races or what you have?, that may offer up a new solution.

No such thing as a fluke. You ran it, you can run it again.