It is not an 'error' message, but more of an informative one. you can turn off this feature from one of the settings in the linker setups. I think that all it is indicating is that it is adding some "pad" bytes of 0x00 to fill out a full S-Record, fox example, if a variable array has 3 elements, and another structure is allocated a few words/bytes higher, the linker could simply generate one S-Record that contained both data elements with "0x00" pad values in between - simply for expediency/optimization purposes.
I might be wrong in this example, but I think this is what it is.