Charger discharging phone

Captivate SGHi897
2.1 Update
Kernel 2.6.29
ECLAIR UCJH7

Original charger that came with phone

I plugged in my charger this morning to charge up the phone for the day.  I checked occasionally looking for the "phone charged" notice on the screen.  Taking longer than normal to charge, so I navigated to the "status" window, and battery status indicates "Discharging".  Plugged it into my wife's charger, same "Discharging" status message.  Unplug the charger and it then says "Not charging".  Battery level is now down to 26%, and still discharging when charger plugged in.  Anybody know what's going on?  I have the phone turned on 24/7, Wi-Fi left on, blue tooth off, and can go a couple days before charging.  Minimum phone use, light texting, light internet use.  Guessing maybe the "smart phone" is doing a "smart battery discharge" and then switch back to "charging"?  Had the phone about 10 months now, this is the first time I noticed this happening.  Can't say this hasn't happened before, as I sometimes charge the phone all night so I'll have a full battery for the day.  Is this a normal thing?

Thanks,
Wkndr

After battery got down to about 20% I turned off phone and plugged in the charger.  It started charging.  Just for the heck of it I turned on phone after full charge and plugged in charger.  It showed charging.  I let it charge all the way up, then turned off phone and charged it all the way again, then turned on  and charged it all the way again.  Sort of followed the sticky above.  Did not see any dust/dirt in the charging port.  Will post again if this happens again.  Maybe somebody out there knows what's up with this.
Wkndr