Just weeks before the failed Christmas terror plot at Detroit Metropolitan Airport, the FBI issued an alert to beauty salons and supply stores in the area to be on the lookout for suspicious people buying certain beauty chemicals, Detroit's Local 4 Defenders reports.

Detroit area salon owners are taking serious heed of the warning; many are keeping logs of customers – particularly if what they want to buy is unusual.

"Before we would get the client card for any chemical service like color, perms and things like that, but now we just get it done with every new client," Southwest Detroit salon owner Maria Martinez-Gonzalez tells Local 4.

While Security Expert Ned Timmons doesn't think the warning is linked to the Christmas Day plot, he says it could be part of a larger intelligence plan to find possible terrorists living in the Detroit area.

"If they send flyers out in the Detroit area, it would sound like there is some cause to believe that intelligence originated in the area," Timmons said.

The focus on beauty supply stores as a potential terrorist place of business came to light following the September arrest of Afghan Najibullah Zazi – who tried to buy large quantities of chemicals from a beauty warehouse in Denver. Intelligence officials allege the chemicals could be mixed to create explosives used in terrorist attacks.