Well, sort of.
According to Douglas Baldwin, the rule is gathered from information in the US Food Code but not succinctly and specifically spelled out, that's why, even after MUCH searching, I wasn't able to find it previously.
Quoting Douglas Baldwin..... "the US Food Code requires that such food can only be between 41°F (5°C) and 130°F (54.4°C) for less than 4 hours (FDA, 2009, 3-501.19)".
So, "40 to 140 in 4" to make it easy to remember and for an added margin of safety!!!