I had the same problem. I bought the Mods4Cars module that gives the car horn response for lock/unlock and it also requires a full 2 seconds of remote transmission to open either trunk. There are a couple other benefits (window control with the remote and so on) but you can search the site for all the info.

This doesn't fix the uncomfortable key in your pocket dilemma but as least you'll know if you've accidentally opened the door or trunk lids.