Is a quick response considered "desperate" or "responsive"?

We were in discussions today with various legal firms (they will remain nameless). We are looking to get some work done so we have briefed the work out to a few firms and looking to see what comes back.

I am writing about one of the firms we met up with. We met for an hour with a partner and briefed him on the work. We discussed rates and estimates at the end of the meeting and he offered to send through a proposal immediately. We thought nothing of it as we thought "as if we will get this straight away"?

Well we were wrong. We not only got it immediately, we got it within the hour :).
In the e-mail it stated the costs and that the partner was in a position to start in the coming days with the first draft of what we wanted next week. WOW!

So do I think that,
a) The firm is desperate for the work and I perhaps should be worried? or
b) They are super responsive and keen for the business and its an example of what I should expect from here on in?

Now in the current climate I should appreciate this behaviour as things aren't that full on for professional services firms, so when a client is there you want to impress them and get their business. But what behaviour is "desperate" rather than appropriately "responsive"?

I like the responsiveness and it always presents an opportunity to negotiate on rates anyway. :)

Anyone have any other thoughts/comments?