GRASS 7.0.0beta3 / statistics change after TIF import?

I'm new to this forum, and pretty much a beginner with GRASS (7.0.0beta3 installed atm).

So my question is the following:

Statistics (mean, min, max) change quite a lot after importing a .TIF grid file (DEM) into GRASS.

According to gdal queries in QGIS, the TIF has the following properties: STATISTICS_MAXIMUM=2.2400000095367 STATISTICS_MEAN=0.05137734831008 STATISTICS_MINIMUM=-3.5300002098083 STATISTICS_STDDEV=0.43984890430363

After import in GRASS, with region set according to this grid (extent & cellsize), GRASS lists the properties as follows:

... minimum: -4.21 maximum: 2.99 ... mean: 0.0451878 standard deviation: 0.435221

Especially the difference in the 'mean' worries me a bit.

I checked extent and cell size, they are identical.

Does anybody have any idea what I am doing wrong?

Thanks!