Sounds good, the brown tips are an indication that those roots are growing - a good thing! It may just be taking its time to recover from its trauma at the store.
I think Carol has a good idea, to check for bugs way down in the bases of the leaves. Maybe take a clean Q-tip and just slide it down into the lowest folds, then see what comes out on there? Use a magnifier if you have one. Mealybugs will appear light colored, pink or white or sometimes slightly yellow. You really don't want to let an infestation get started.
