[Sciencewoman]

The Panhellenic on the campus where I teach and advise has established a minimum 2.6 GPA for sophomores+ and transfers, as a condition of recruitment registration, and they do require a grade release to look up a PNM's grades. They also state that this is the minimum to participate, but chapters may privately require or look for higher GPAs. All freshman are considered to be in good standing/eligible for fall recruitment. They will make exceptions for lower GPA students with a learning or medical disability that is documented in writing by the PNM's physician, but again they specify that individual chapters may still require or look for a higher GPA during membership selection.

It sounds to me like like Panhellenic:

1) has a minimum, didn't realize until later on that the PNM didn't meet it, and was letting her know. This doesn't seem likely, since she later received a bid, but if they called her in (which also seems odd...usually a released PNM is contacted by her Rho Chi/Gamma, but this may be handled differently on your campus), it might have been their error to not catch it, and they decided to make an exception and allow her to accept a bid through COB, or
2) she was released from recruitment and they were trying to let her down gently ("it's your grades, not that you weren't liked"), the reason(s) for which they'd have no way of knowing since membership selection is private, and
3) COB resulted because some chapter(s) didn't make quota/total or had someone decline to accept a bid, and were eligible to COB, so they went back to the pool and decided to make an exception and extend a bid to this PNM.

That's my best guess. In the end, it sounds like it all worked out, and everyone is happy! Congratulations to her and to you on joining Chi Omega!