Why did my Case Status jump from Request for Evidence to Post-Decision Activity ?

[takatak]

I'm tracking my mother's case via this USCIS LINK after submitting Form I-130 back in mid 09

A literal translation of my vernacular birth certificate was submitted in December '09 after which the status showed that they made a Request for Evidence and received the same.

Now this morning, the status says

On December 28, 2009, we mailed you a notice that we have approved this I130 IMMIGRANT PETITION FOR RELATIVE, FIANCE(E), OR ORPHAN. Please follow any instructions on the notice. If you move before you receive the notice, call customer service at 1-800-375-5283.

And now my case is under Post-Decision Activity. No testing or interview has been conducted so far.

[takatak]

furthermore, the priority date on the Notice of Action is listed as June 15, 2009 so 5 and 1/2 months between filing & approval seems about right.

How long does it generally take for the NVC in NH to handle their end of the bargain after the regional service center forwards them the paperwork ?

[takatak]

got an email from the NVC asking me to pay another $400 @ http://travel.state.gov/visa/immigra...info_3906.html

any clues on what lies next after i pony up the cash ?