Thanks.
I looked at the TSA website --evidently blocks of cheese are okay, which is odd because I can think of nothing more like C4 than a block of mozzerella. The list doesn't mention cream cheese on bagels, but I've seen a couple of reports from FTers saying that had their bagels and cream cheese confiscated.
I'm flying UA -- maybe I'll just get one of those buy-on-board delightful snack boxes.