Yeah, it'll probably be cause to have your carry on opened and checked out by the guy at the walk through xray. Every time I've had something electronic in my carry on, they've checked it.
When I flew to LAX from Detroit, I had my keys with me because I had drove up to the airport, rather then getting someone to drop me off. Well, silly me, I also have a 45 bullet on my keychain. It's made to the US Army's specs as a dummy round (hole drilled into the side of the case about half way up). In addition, I had popped out the primer and stuck the little chain in there and soldered it. It couldn't be made functional at all, not without another case (and then why would I bring it like that, the case would have shown up in my damn carry on). Well, I dropped my keys in the little tray, walked through the metal detector (boots didn't set it off even), and on the other side, the security guard was holding my keys, by the bullet. I tried to explain it couldn't be made to fire, but she wouldn't listen. I had to go back, check it in one of my carry ons (I had packed light into two carry ons to avoid checking my bags...) before they'd let me on the plane. In retrospect, it WAS my fault, but it was pretty damn obvious that bullet wasn't going to fire.
And here's karma for you, less then two weeks later, the damn thing fell off my keychain and I lost it.