Did news of Robb taking the Crag arrive at Riverrun before or after Catelyn released Jaime? The text seems inconsistent on this point. At the beginning of ACOK Catelyn VII, mention is made of the small folk celebrating ‘Edmure’s imminent return and Robb’s conquest of the Crag’ but the first mention of a raven from the Crag isn’t until ASOS Catelyn I.

The confusing issue here is that there’s multiple sources of information about the Crag: 

1. In Catelyn VI ACOK, there’s word that Robb has marched on the Crag.
2. In Catelyn VII ACOK, they receive word that Robb has taken the Crag. 
3. In Catelyn I ASOS, they receive word from Robb himself that he took an injury.

So I would say that the news arrives before Catelyn releases Jaime.