Renters Finding Mold

[Orlando Barron]

Hi all,

Long intro- sorry.  So our new renters moved into one of our units on the first of July, since moving in, they have had a laundry list of items they are requesting to fix. 
On one of their finds, they told us that they found black mold in the kitchen and bathroom, which is interesting since I painted and redid the faucets in those two areas, and saw none.  
They took photos of the mold and then cleaned it off.  They did not address this to us until a phone call we had with them today about a few other items they wanted changed.  
What we are thinking of now doing is hiring a mold inspection company to check out their unit and make sure their claims are valid. The renters are also stating that they found mold in the dryer vent and have since cleaned it.  Is there anything else we should possibly do to avoid any problems down the road?  

Any guidance and input is greatly appreciated, 

Thanks!