Bumps can only be given once every 6 hours.
During that time, the system will not allow a bump and you should see a red timer showing when the next bump will be. However if you click your back button, you might be able to see the "bump now" button again. Even if it's there, they system will stop you and give you that "you don't have permissions" page.
Most likely it wasn't 6 hrs yet, but you some how saw the bump button. That's why it prevented the bump. That was about 1 hr 30 mins ago, so maybe it passed 6 hrs which is why it worked again.