We reported in ATEL#2873 (Negoro et al.) that MAXI/GSC detected a new X-ray transient, MAXI J1659-152 at (RA,Dec)=(264.79, -15.27) (J2000), whose position is consistent with the location of GRB100925A reported in GCN#11296 (Mangano et al.).
The GSC light curve since UT 2010-09-21 00:00 (MJD 55460.0) is shown in the below. The X-ray brightening seems to start around 2010-09-25 00:00 (MJD 55464.0) . The latest light-curve data will be updated on the data-product web page.