Hi LookingNow,
It certainly could be … or it could also be because the current layering isn’t the best match for you. There is more in post #2 here about some of the more common “symptoms” on a mattress and some of the possible reasons behind them. The first thing I would always do though is to talk with the manufacturer because they will be more familiar with their mattresses and how different types of people do with different combinations than anyone and you can go into much more detail with them about the specifics of your “symptoms” than is possible on a forum.
I’m not sure where you read this but a softer layer over a firmer layer would be much more common than the other way around … especially in the top two layers (although the other way around or what I call dominant layers can also be a useful option in some cases). Most layering combinations have the firmer layers closer to the bottom. Like Neal suggested I would also tend to stay with the initial FFM for a while before switching things around but if this is impossible then I would definitely talk with Neal about your options. Two of the options you have to rearrange your layers would be what you have tried (FMF) which would give you a firmer sleeping surface and a little less deeper support or FM (two layers) which would give you a support layer that became firmer faster than having two layers and a little firmer sleeping surface. Additional options would also be possible with a layer exchange depending on the outcome of your conversations with him.
Phoenix