Why do I need to constantly enter a passphrase in SSH?

I am using Ubuntu 13.10 and have a passphrase on my SSH key. Until a few days ago, I did not have to use my key after I resolved it with Git projects, etc., but now every operation I perform with SSH (whether pressing Git or logging into other systems) asking me enter passphrase.

I look at other answers here and it suggests changing the chmod of the SSH id_rsaxxx files to 600. I did this, but it did not work.

The only thing that, in my opinion, has changed is the implementation of several OS updates, maybe this caused it? Otherwise what? I do not want to enter the key every time I perform a simple operation.