warning: size of values file does not match the number of cell

Hi,

I have a large raster file (netcdf) that I am trying to process ie

bathr

class       : RasterLayer
dimensions  : 10800, 21600, 233280000  (nrow, ncol, ncell)
resolution  : 0.01666667, 0.01666667  (x, y)
extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
coord. ref. : NA
data source : /work/up/common/bathymetry/ETOPO1/ETOPO1_Ice_c_gmt4.nc
names       : z
values      : -10803, 8333  (min, max)
zvar        : z

Processing this with aggregate() gives the following warning:

min.bath <- aggregate(bathr,fact=out.agg,fun=min,expand=FALSE)

Warning message:
In .rasterFromRasterFile(grdfile, band = band, objecttype) :
  size of values file does not match the number of cells (given the data type)

What does this warning mean? I've seen previously on the list that
there was a bug associated with this warning - the message has only
appeared for me since upgrading from about raster 2.0-12 (can't
remember the exact version, unfortunately) to 2.0-31.

Best wishes,

Mark