Buttons get blocked

*What I expected to happen was ...
The button was suposed to send a redstone signal, and once sended, it should had desactivated itself.

What actually happened was...:
Instead of stopping sending the redstone signal, it got blocked. After 28 seconds, it stopped sending the signal

Steps to Reproduce:
1. Place a command block
2. Write a simple command on it
3. Place a button on some dirt far from the command block (not too far)
4. Put redstone to connect the button and the command block
5. Pulse the button
6. You will notice that the button gets stucked, and continues sending the redstone signal.
7. After 28 seconds aprox. the button stops sending the signal.