Jailbroken iPhone, iOS 5.1.1 suddenly has new diagnostic apps I jailbroke my iPhone so that I could make use of the F.lux app which allows me to sort of dim my screen with an orange hue so that I could read on a flight I took recently without annoying other passengers. I'm home now, though, so I don't mine un-jailbreaking.

With that out of the way, here's what's happened. A few days ago I was reading and my phone froze for a moment and the new voicemail popup appeared and told me that I had 2 new voicemails, which I didn't have, and then the camera light turned on and stayed on. So I rebooted the phone and it was fine. But now, moments ago, 4 new apps appeared, seemingly at random, on the home screen - AdSheet, FieldTest, iOS Diagnostics, and Setup. All 4 of them have blank, white icons.

Should I be concerned about a possible security breach of my phone or is this some of the unexpected behavior that one could expect once they jailbreak?

Also, I applied the PDF fix from Cydia and changed my SSH password immediately after jailbreaking. I don't know if that info is important, but is given here for completeness.
This bug occasionally happens to me when I install new apps or update existing ones. All the apps you've listed are built into the phone, but do not have icons by default. Respringing or restarting the phone always works to rehide them. Have you tried that yet?