Firefox 13.0.1 forgets keychain permissions?

I just updated Firefox to version 13.0.1 yesterday. Since the update, each time I relaunch Firefox, OSX asks for permission to allow Firefox to access the keychain. I click yes, Always Allow. Then the next time I launch Firefox, it happens again. Before this, I had it set so that after the initial Always Allow permission was granted, there would be no further requests until the next Firefox update.

I'm wondering whether this is an intrinsic (and very annoying) security feature of the new Firefox release. Or whether something has happened with an addon or some other bit of software that's screwing things up (I think NoScript got an update yesterday too).

Running OS X 10.6.8.

Anybody else experiencing this?

It's LastPass causing a problem

Through a process of elimination, I went through my Firefox addons and determined that it's not NoScript. The problem is LastPass.
When LastPass is the only software disabled, no problems. As soon as it's turned back on, the keychain permissions harassment starts up again.

I don't think my version of LastPass has been updated recently. So there seems to be a glitch in how Firefox 13.0.1 and LastPass interact as far as keychain access goes.

That was it.
I downgraded Firefox from 13.0.1 back to a version of 12.0. Left LastPass and other addons the same. Now everything works the way it was working before.

Serves me right for breaking my usual rule of waiting a few weeks before updating to the latest Firefox release.

(There doesn't seem to be any discussion of this issue on the LastPass site as yet.)

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Not entirely sure if this is the same specific issue (too technical for me), but there has been at least some discussion over at Mozilla about compatibility problems between Firefox 13.0.1 and LastPass
https://bugzilla.mozilla.org/show_bug.cgi?id=761598