one-time ABS wierdness drains battery?

Hi all, this is a strange one.

I left to pay a bill in my '96 SW2 wagon, and at the first intersection,
about when I always get the short wierd wind-up noise each trip that I'm
told is the ABS system, I got some traction control thumps (with indicator
light) instead, and my brake and ABS warning lights came on. I noticed I
could still brake so I went on and paid the bill. The brake and ABS warning
lights stayed on through the 10 mile drive.

When I came out from paying the bill (about 5 min.), I had a dead battery,
which could barely lock the doors. It was as if my alternator had quit at
the beginning of the trip, but a 10 minute jump did nothing at all. So I
went and bought a battery, installed it, then started the car with it. No
warning lights, normal operation ever since. It's been 4 days.

Any ideas what the heck happened, and what I should watch for? I won't be
taking any trips with the brake and ABS lights on again, that's for sure.