Yes, I see the water stain but I don’t believe you have a mold issue.
If you have a tenant who thinks that they have mold due to a leak, check into it. The fear of living in a moldy environment will drive tenants to be vocal about any water issues that they may have inside their unit. Bringing in a third party contractor may quickly resolve any concerns.
Most mold issues can be seen and can be obvious at first sight. But what about the water stain from a roof leak? You can see the discolored drywall, does that mean you have mold? That will depend on several things.
Is the stain new? If there was a recent storm and now you have a water stain, the area may just be wet and needs to be corrected. If the stain is growing, getting darker and soft to the touch, you may have a problem.
How is the ventilation?A one-time small leak may often times be wiped up and dried quickly with fans and blowers. If this leak is in a dark enclosed area, it will remain moist for a very long time. A situation like this could promote mold growth.
Has the source of the problem been corrected? This is the most important thing; you must correct the source of the problem. A leaky roof needs to be patched, a dripping pipe needs to be repaired or a cracked drain pipe needs to be corrected.
A contractor with experience in water damage and dry rot damage can use his experience to better determine the extent of the damage and the proper correction. Often times getting a third party to look at the problem will relieve the fears that the tenant may have with mold.