Let's

I'm interpreting it as the flavor of honey being a hint of unexpected, but not overwhelming aftertaste you don't notice until the end.

I think the sandwich is supposed to be sour and sweet. Cause for both men the memory is sad and beautiful at the same time and so associate the bee with the bittersweet feeling from the meal and the memory (=・ω・=)
I don't know if I make sense...

Most likely he put too much honey to it that the taste is too obvious. Hence, the bee (￣∇￣")