does Paul quote Hosea from memory?

The concept of "memory," especially of "social memory," is a live issue among New Testament scholars. (Social memory refers to a field of inquiry within the Humanities that raises questions about the social distribution, function, and contestation of knowledge about the past. In other words, how do humans, as part of the social groups of which they find themselves members, remember, utilize, and argue about the images, narratives, and rituals of the past?) I'm certain that social memory research holds potential for Pauline scholarship just as much as it has opened up new questions and routes of inquiry in Jesus scholarship, but I don't know specifically how.

As I was working on my comments on Romans 9 for a graduate course I'm teaching, I noted that Paul's citation of Hosea (and Isaiah, too) in this chapters seems a bit haphazard. Robert Jewett (Romans [Hermeneia; Minneapolis: Fortress Press, 2007], 599) provides a nice chart showing how re-arranged is Paul's citation(s) from Hosea 2:

It might be difficult to read, but the basic point is that Paul cites passages from Hosea in the following order:

• Hos. 2.25c
• Hos. 2.25b
• Hos. 2.1b
• Hos. 2.1c

My question: Does this suggest that Paul is citing Hosea from memory? Does it matter that neither his citations from Hosea here or of Isaiah in 9.27–29 exactly match the Septuagintal form of either text? If Paul is citing from memory, does this offer us a glimpse into how the traditions as well as the written texts of the Hebrew Bible worked (or functioned) in early Christian memory?