If by recent, you mean this past fall, then I'd say it was in line with a combination of fear of muni bond defaults plus a shift from bond funds to stock funds by the typical investor.
The real question to ask is "Have muni bond fund prices fallen far enough to make an investment in them virtually risk-free?"
For the leveraged muni bond funds, I would say no. Several states/counties have not yet gotten their budgets adequately together, so the risk of defaults is still higher than I'm comfortable with. It's only going to take a single default in one of the key states to create a domino effect on muni bond prices.
For a targeted, non-leveraged muni bond fund (e.g. there are two that specialize in only Oregon munis), then I think it's reasonably safe.