Thanks Mark and John and others for the help with this.
So, if I've identified the source of the leak correctly, it's from these three shift lever bolts on the driver's side. Wow...what is the chance that all 3 O-rings started leaking on me at the same time?!
Does it sound like possibly these rings might not have been there in the first place (rather than all failing)?
It must be a slow leak, because when I checked the fluid with the "first knuckle test" - the fluid level is still ok. The spots on the garage floor that it leaves are not that big, but the trans bottom always seems to stay wet. Could it also be that the gear oil, when it leaks out, just clings to the bottom of the trans and makes the leak look worse than it is?
Thank you!