An uptick in sales leads is not necessarily going to convert to more sales. If your webinars are attracting a lot of attention, it doesn't always mean customers are interested in buying. When the economy turns bad, big companies cut discretionary spending first and then later they come back to cut headcount. In the interim, there are a lot of employees with nothing to do except "test drive" new products and services.
Instead, watch revenue and sales cycle. Those two are the leading indicator of things to come. Sales leads could actually tick up in a down economy but that is most likely misleading.