No, it's not a coincidence. But the fact that the Federals burned the place before they got there, takes your imputation of a Virginia assault on the arsenal off the table. Ditto the Gosport shipyard and works at Norfolk.
You can't charge people with stealing a burnt-down building.
And there was no confrontation.
No, the fact that the Virginia milita were on the way to Harper's Ferry to seize the federal arsenal weeks before the people approved secession is no coincidence at all. They were active participants in the rebellion before the legislature approved secession in the first place. So why should you be complaining about the fact that the government responded?