If your self lever has been installed for a few days and sounds "solid" when tapped you should be OK. Perhaps call Mapei - one of their new reps lives in Victoria and was a setter for years, I'm blanking on his name.
Some times when you get cracks like this it is a sign of over watering the self leveller.
You might wait another four days and try one of my rules for tiling. "Never tile anything you can't hit with a hammer". If you give a few well placed blows to the floor (in between heating wires) and you don't blow away your prep or your prep work doesn't crumble it should be OK.