Danny learned the reason why both his adopted parents and the GIW find it a little hard to somewhat track him down in human form (unlike when he's in ghost form) is because when he was still in the LOA he learned to suppress his presence (he was always good stealth, blending in, and other things like that, unlike his brother who didn't have the patience for it) and he does it subconsciously in human form but not in ghost form.
After finding that out he starts to train his ghost form to suppress his core/presence to that nearly of a blob ghost (and boy has it been fun being able to sneak his way into fights when his rogues come to town. Skulker is both the best and worst, he enjoys the challenge, Danny won't lie he enjoys testing his abilities against the 'greatest hunter')
Once Danny got a good handle on it, his parents suddenly burst into his room and announced that they're heading to Gotham tonight!
Cause apparently that 'ghost scum' ecto-signature has been detected there and they finally found it after months of recalibrating their inventions to find his trail. (And where his parents went the GIW have their eyes in his parents which meant they're not to far behind)
Danny is stunned (he forgot Damian and his DNA were very similar due to being 'hand-crafted' and the fact they grew up around the Lazarus Pits, that Danny suspected was dirty ecto now)