Historically, a much better indicator to watch out for has been large increases in debt (relative to incomes) for several years in succession. As Reinhart and Rogoff have documented, financial crises are often followed by tough economic times.
But even without a financial crisis, periods of rapid increases in debt tend to be followed by periods of economic stress – recessions that last longer and prove more troublesome than a “plain vanilla” recession, in which any lost output is recovered very quickly (New Zealand’s mild 1998 recession might have been an example of that sort of recession).