My guess is that it is (somewhat) acedic. Acids on marble will dull the finish. If you don't see any now, and you rinsed it off well, you should be okay.
Not a pro, multiple Schluter Workshops (Schluterville and 2013 and 2014 at Schluter Headquarters),
Mapei Training 2014, Laticrete Workshop 2014, and Longtime Forum Participant.