I was right even though I was wrong. [Previous post edited on May 4th (for content) and again (for clarity) on May 11th.] Yes, Flaccus became Governor in 32, but he died in 33 and there's no record he was replaced before Vitellius came in 35. So Aretas still saw ~10.5 of 12 years where Syria had no Governor.
Bowersock says: "When Philip died in 34, there was probably no governor at all in Syria, and if there was, he was probably no great threat to Aretas... Tiberius had, for reasons best known to himself, kept the governor of Syria out of his province for ten years.* Aretas can have had no great reason to think that the Romans would worry excessively about the newly acquired and difficult terrain in the south of the Syrian province." (I'd even hilighted the long footnote under "ten years" which mentions Flaccus and explains the record from 32 to 35.)
So I knew about the footnote on Flaccus, but my memory held onto the text "no governor" and "ten years". How about that? ;)
Point one: Flaccus shouldn't have surprised me, but that's what this job is like. TONS of info to keep track of. My post last night is still a good example of what happens when two pieces of information are kept in different mental files, topically... even though they also belong together! (Sure, it's a hard tendency to fight, but we don't have to dwell there.)
Point two: it still looks strongly like there WAS in fact NO governor of Syria when Philip died in 33/34. So maybe nothing was really substantially off about my summary, two years ago.
One new thought this weekend, however. We should consider that Aretas was shrewd enough to ape Syllaeus' methods during the Trachonite rebellion of 12-9 BC. That is, the old King remembered what his first rival had done the last time their nation made a serious play for Trachonitis. Perhaps, instead of encroaching on Trachnonitis with his own military, Aretas was using agents to stir up the heavily Arab population in the region to do their own thing.
So then the question is: why did Aretas make a full military assault on Gamala?
Much more left to suss out...