Reply #12: "for some reason the leadership kept the vote open for over an hour"

[suffragette]

This has been confusing to me. I see it mentioned frequently, but have yet to see a reason why this occurred.
The implication from it seems to be that a choice was available there, to keep the vote open or to have shut it down at some point, which means it could have been shut down by the Democrats when it was first noticed that the Republicans were switching votes , but before they had switched enought to make a difference. If that is really what the leadership wanted, or did they?

So,
was this an error made by the Serrano?
was it done on purpose for some reason?
is there some rule not being mentioned that impacted this?

Can someone who knows more explain this?