My app has been in the play store for a while, and it worked. Yesterday I released an update, and found a bug in it, which I want to fix today. After uploading my alpha apk
As I suspected, I just had to wait a couple hours. :(
edit:to give a bit more info, this is the same thing that happens when you buy an in app item on one device, and the other device with the same google account is not in sync for a while. It's just that the google servers are not updated fast enough.