They may need replacing, but before that is done I would put them on a good "portable smart charger". They may not be getting a full complete charge through your coach charging system & may benefit from an "equalization" charge which can only be accomplished with a Smart charger. Equalization charges at a range of 15 - 16 volts & is required occasionally for lead acid deep cycle batteries.
Even if the batteries turn out to be bad & you have to buy a "smart charger" to do this, the charger & information below can be beneficial for the future.
Here is a link concerning deep cycle battery maintenance:
The 12volt Side of Life (Part 1)
www.marxrv.com/12volt/12volt.htm