It's my understanding that the FDA only requires trans-fats to be listed when they come from what we traditionally think of as lipids/"fats" (triglycerides). It would appear mono and di-glycerides are excused from this requirement.
It is likely that they contain trans-fats, as they're typically/(exclusively?) high-heat processed with hydrogen and a metal catalyst, just like traditional triglyceride-based trans-fats. I don't believe it matters if the source material is animal or plant derived.
The good news is: the actual amount is fairly low and thus probably not worth a terrible amount of concern, but as a general rule, I try to avoid them.