Did your receipt number begin with WAC or EAC?
Did it change to EAC?..Or did I miss something?
Asked that 3 hours ago on the phone with uscis.
Best answer I got was more or less (du-huh).
Anyone know why wac is eac now?

LWG-

EAC will indicate Vermont Service Center with WAC being California. Even though you may have forwarded your application to a certain center, where your NOA1 is issued from is your leading indicator for those first three numbers with regard to and I130 or 129F - I have not gotten further down the road to see if we get more numbers to screw up our heads with but yes I know there will be.

Cheers and hopefully I understood your question correctly.

The only thing that I can think of is that they moved your petition to the Vermont Service Center...FYI: the 3 letters before your receipt number mean:

WAC - CSC
LIN - NSC
SRC - TSC
EAC - VSC

I am sure someone else will clarify for you, but this may be the reason.

From what I understand the "E" number means a file has gone East (Vermont) and a "W" number means its gone West (California) for processing. It's a toss up.....the Petitioner's location or office where the original I-130 was sent has no bearing on where it ends up.