I haven't found a fix yet, but using the search button brought up several past posts on the BAS ESP topic. There was enough info in those threads to give me an idea of what the potential problems/fixes are.
Later today I will try the steering wheel centering fix. Although the post doesn't say if you should wait until the light is on to perform this fix, and it isn't clear which exact position the ignition key should be in, ie the first detent with no dash lights on, or the second detent with dash lights on.

Interestingly, one of the posts mentioned a "rough road" code as a possible indicator. Evidently a rough road can throw off wheel speed sensors or some other component of the system. I've owned my car for a year and a half and driven it about 8k miles, and the light has never come on until last week---------one month ago I moved and one of the new roads I now drive on is EXTREMELY rough. So rough in fact that some of the posts about owners having their wheels break over rough roads/potholes have remained in my mind. So maybe the rough road code will be the indicator in this case. I'll take the car to the Jeff City dealer next week.