Drywall after leak - remove or just let dry?

[Rob C.]

I'm a pretty new landlord here, and I recently had a leak in my rental property from the upstairs bathroom going to the downstairs living room ceiling. Nothing major. I had a plumber come out today (about 72 hours after my tenant noticed the leak) and he concluded it to be the fault of the shower valve, which he repaired rather easily. He cut out about a square foot of drywall on the ceiling to diagnose the problem. The water stain though actually extends quite a bit beyond the hole he cut out in the ceiling. Despite the stain, the drywall is stiff and dry to the touch. I wanted to get the opinions of all the smart people on this forum on whether the rest of the stained drywall really ought to be removed (to prevent further problems, e.g. mold), or if it would suffice to just to let it sit for a little bit longer (i.e. to make sure any possible moisture is dried out)  before applying kilz and painting over it. Thanks in advance for any shared opinions, Rob