Salve, Amici.
Certainly sounds right! As you said, Roman naming conventions had become quite flexible by that time, as evidenced by the fact that Roman women were acquiring names of more variety, adopting their own distinctive, feminine cognomina.
-- Nephele
This might be too off-topic to keep in here, and perhaps should be split off...I'll let the mods take care of that. But...
Why was this acceptable at the time of Vespasian? Were women given more rights in society, and therefore adding the feminine-line to the name was acceptable? Or was it simply to be more distinguished?
It would seem to me that if it became acceptable to put the feminine-line to the name, then matrons of the family (not necessarily matriarchs) started to weild more influence and/or power. It's a big step in such a patriarchal world. I know that, as a whole, (patrician) women in Rome had more power and rights (for lack of better terms) than the (elite) women of ancient Greece, but they still weren't exactly 'liberated' in the modern sense.