They put some tar chemical in the rubber to make it more flexible. It's usually only a problem with products imported from China.
EDIT: It's called rubber softener in English ;-) and includes chemicals such as phtalates, sulfides and stuff like that.
Basically, if it smells really strong you know it's not good.
I'm not very concerned though, I just thought I should mention it. Let's say it were flip-flops, I wouldn't want to wear them, but a guitar stand, meh.... - don't lick it :-) and try not to touch the rubber parts too much.
The stands from Warwick for example don't have this.