  We draw attention to some intriguing coincident patterns in the optical light
curves of NGC 4151 and NGC 5548. Inspecting the light curves of these two
classic Seyferts, we find evidence for at least five occurrences of a similar
sequence of variations. This pattern consists of a ~ 2 yr long sequence of
shorter flares, with a total energy of 3--5 10^{50} ergs in the B-band. We
predict that the on-going monitoring campain on NGC 5548 should soon reveal
more occurrences of this general pattern if it is truly recurrent. We speculate
on the possibility that this pattern is associated with a fundamental/universal
`unit' of variability in active galaxies, and discuss a possible connection
with the variability properties of QSOs.
