Intermittent trouble with electronic "key"

The neat little remote unlocking and locking key thing I have has started to not work from time to time. I'll press the unlock button and nothing will happen, or I will get out of the car and press the lock and nothing will happen.

Tonight, the "alarm" started going off while we were upstairs in the house... like I had pressed the panic button on the "key". It shut off when I went downstairs and pressed unlock.

Anyway, it's happening very rarely... but it is of some concern to me. I would hate to not be able to get into the car when it came time to drive home from school.

Theories? Should I get the "key" replaced? Are there batteries that just need replacing? Is it a larger electronic problem?