The GPM project has reprocessed all the original NRT IMERG data both EARLY and LATE to product version V04A. In addition, this reprocessing brought the IMERG dataset back to the beginning of the GPM mission in March 2014. The original NRT IMERG started its processing in March of 2015.
Currently only the HDF5 products have been reprocessed to V04A. The TIFF/TFW versions will also be reprocessed but this will take a while longer.