Why did the xenomorph leak on two different individuals without causing any burns?

The xeno's blood has consistently been shown to be a highly corrosive acid throughout the extended alien universe, therefore I believe we have to assume that the "leak" is a bodily fluid other than blood. In Aliens the xenomorphs made a hive probably out of some bodily secretions and they also held victims captive with some type of sticky goo in the hive.  Perhaps this is what the xeno leak in the TV show is. 

I can't recall the details but wasn't it xeno drool and not it's acid blood? The former isn't corrosive I think. 

Is there a difference?