I will just have to see if the normal behavior resumes (turned SmartReflex off).. When I unplugged the phone now, i.e., after 8 hours of charging, the reported battery level is 74%. Yesterday, it was 96% after 4 hours of charging and 4 hours of being plugged in and reporting full (green led when idle).

Actually, there is one more thing I should mention. Today, after about 3 hours of charging, the status bar battery indicator stopped moving, it did not stay at full but at some 70%. When I locked the screen, the yellow light was still blinking and the X-term command reported that the N900 is charging. After reboot, the status bar battey icon started moving again. This may have been the first sign of something around charging going wrong...