Is this version affected ( A1 ), it was built in Apr 08. But I believe the motherboard was changed once in 2010 for no video. So not sure if still this also has problems. My warranty expires next month, so wondering if I should get it done now.
01:00.0 VGA compatible controller: nVidia Corporation G84M [Quadro NVS 140M] (rev a1) (prog-if 00 [VGA controller])
Subsystem: Lenovo ThinkPad T61
Flags: bus master, fast devsel, latency 0, IRQ 16
Memory at d6000000 (32-bit, non-prefetchable) [size=16M]
Memory at e0000000 (64-bit, prefetchable) [size=256M]
Memory at d4000000 (64-bit, non-prefetchable) [size=32M]
I/O ports at 2000 [size=128]
Expansion ROM at <unassigned> [disabled]
Capabilities:  Power Management version 2
Capabilities:  MSI: Enable- Count=1/1 Maskable- 64bit+
Capabilities:  Express Endpoint, MSI 00
Capabilities:  Virtual Channel
Capabilities:  Power Budgeting <?>
Capabilities:  Vendor Specific Information: ID=0001 Rev=1 Len=024 <?>
Kernel driver in use: nvidia
Any T61 or T61p using Nvidia graphics with a bottom label date code of 08/08, 08/09, 08/10, 08/11, 08/12, 09/01, 09/02 and possibly 09/03 (Aug 08 thru end of production around Feb or March 2009 was build with the "fix". The transition from the vulnerable units to the "fixed" units happened during July 2008 (08/07) so conceivably 50% of the July 2008 units could have had the "fix" incorporated from the factory but there is no way to tell as I do not believe they changed the motherboard version ..... only the soldering material inside the Nvidia chip and I do not know if Nvidia changed part or version numbers on that "fixed" chip. That means some A1 chips may possibly be the "fixed" ones and some not. Most all A2 versions, however appear to be of the "fixed" flavor.
Your Apr 08 (08/04) machine, if never serviced in 2010, could still be vulnerable to the defective Nvidia chip. However, since you had the video problems resolved in 2010, I would venture to say you have a "fixed" graphics chip ...... Lenovo knew about the issue a far back as late 2008 so I'm confident they were using "fixed" batches of Nvidia chips (either A1 or A2) thoughout 2010.
Although my Aug 2008 unit has the A2 version graphics, that does not mean that all the A1 versions were "un-fixed." You can double-check your current graphics version using the reliable and accurate free utility CPU-Z v1.57 and report back if you wish.