Corporate sales types have used the phrase "face-to-face sales" since at least the early 80s to refer to a sales pitch made in person, as opposed to a telephone pitch or a "drive-by" (a pitch that consists of nothing more than dropping off product literature):

"Amekor Industries beats the increasing cost of face-to-face sales calls by relying on the telephone approach." —Carol Rose Carey, "Technoqies for Ringing Up Orders," Inc., November, 1982

Using the phrase to refer to retail sales in a physical store became popular in the late 80s and early 90s when mail-order shopping was in vogue:

"For much of the 1980's, mail-order sales grew by about 15 percent a year. That was triple the growth rate of most department stores and other retailers that depend on face-to-face sales." —Eben Shapiro, "The War of the Christmas Catalogues," The New York Times, November 15, 1991

But the phrase has really picked up steam over the past couple of years as online retail has become a popular alternative to fighting the hordes down at the mall.