They started being a lot more inquisitive about food other than fresh meat and vegetables/fruit/seeds after the last foot-and-mouth disease outbreak in the UK. I have once at PHL been randomly selected to go through a secondary food inspection on arrival - they put your luggage through a screening machine.

I have been told of cases where they were very fussy about/suspicious of chocolate.

If you run into trouble, go for Ghirardelli, Scharffenberger, Godiva or even See's. Any of these are good-quality chocolates! (In fact, I'd far rather eat any of them than Cadbury's, but there's no point initiating culture wars.)

wg