soft spot in floor

[fireleu6169]

So I found a soft spot in the floor in front of the fridge. I pulled up some of the flooring and the top layer is ok, but it feels like what is underneath is gone. Looking around under the kitchen cabinets and in the bathroom I don't see any signs of water damage.It seems like it is soft between a pair of 2 x 4's. We haven't had any rain since I bought it (Northern Calif.) My Que is an 06, has anyone replaced their subfloor ? wondering if I should wet test it before I fix the spot.

[vcrt]

A moisture meter is a very useful tool to have when you own a camper, but since you have already pulled up the floor covering, you could use a small hole saw to remove a plug of wood flooring. That will tell you tell you the condition of the wood below and you'll know if any mold is present by what you see and what you can smell.
If it's become damp you'll have to first find the source of the water intrusion and fix it, then cut out the affected area and replace that along with any insulation below it.
Rich