Bukkit

What steps will reproduce the problem?
1. Player creates shop, clicks sign to select item
2. If exiting screen fast enough, player stays in creative
3.

What is the expected output? What do you see instead?
The player is being put into creative when they select the item and if they exit fast enough, they can stay in creative.

What version of the product are you using?
Shop 1.4.8, Spigot 1.7.9

Do you have an error log of what happened?
No error is produced.

Please provide any additional information below.
I wasn't able to produce this but I tested it ranked as staff, but two players reported that they were put into creative when creating the sell sign and stayed in creative when they exited out. Obviously I had to remove the plugin as this is a huge exploit.