  The first experimental evidence for direct CP violation in charm-quark decays
has recently been presented by the LHCb collaboration in the difference between
the D -> K+ K- and D -> pi+ pi- time-integrated CP asymmetries. We estimate the
size of the effects that can be expected within the Standard Model and find
that at leading order in 1/mc they are an order of magnitude smaller. However,
tree-level annihilation type amplitudes are known to be large experimentally.
This implies that certain formally 1/mc-suppressed penguin amplitudes could
plausibly account for the LHCb measurement. Simultaneously, the flavor-breaking
parts of these amplitudes could explain the large difference between the D ->
K+ K- and D -> pi+ pi- decay rates.
