I usually eat candies and drinks with an OU on it. I wanted to know if it is OK to also eat gushers, a product which includes in it ‘white grape juice concentrate’. Is there something we are more careful with, as Lubavitchers, regarding Stam Yeinom, that others (and other Hashgochas) are not?
There is no reason to be concerned about Stam Yeinom in this case. However, there is a non-Halachic Chumra of Reiyas Nochri that many Hechsherim are not concerned with, as it has no Halachic source.
Many Chassidim are particular about this, often just with wine for Kiddush, Havdalah, etc. Others are careful with all usages of wine.
See here for more details.