I've never understood the "new tire" theory. According to our wholesale tire Rep., the only place mold release agent is used at all anymore is on the sidewall so the fine print is readable, nothing on the tread at all.
I've never noticed any new tire problems, and if they're the same brand/type of tires, I scuff a new rear tire from edge to edge within 5 miles from the shop. Always makes me wonder when I hear these kind of stories.
Glad you made the save though. Would have been ugly to dump it right in front of a cop.