It could be a transplant shock but it's also means that you did mystikes while tranplanting , if you've harmed the roots or if your medium is not the same then the plant could have been shocked and takes some days to recover , you also could have over watered just after the tranplant but it seems that you have found a way to not overwatering whild bringing nutrients thanks to
@Ga4rd2en0er, so I supossed that it can't neither be an under watering as you have the hand on your routine
Personnaly I can't say why because all of the classic answers seems not to fit your case