2007 Honda Accord EX, 2.4L MFI DOHC 4cyl

I recently changed the air filter in my accord. I changed the air filter, no real problems. The next day when I got to work, I hit the lock button on the keyless entry system twice, which should trigger a honk, and nothing happened. I went closer and tried it again and noticed that the car does in fact lock and the brake lights light up for a second, but the car does not honk. I then tried the panic button and nothing happened. I went inside the car and tried to honk the horn and it worked with no problems.

My first guess was the battery in the keyless remote, but once I figured out that the lock/unlock mechanism works, I kinda ruled that out. I am thinking now it has something to do with the alarm system, but have no idea where to start.

Any ideas? Any help you can provide would be greatly appreciated.

Sorry, I forgot to mention that this is the standard keyless entry/alarm system for the 2007 honda accord. No after market alarm or anything like that.