The TICKETS, that I'm holding in my hot little hand definitely say B/4911 and B/4810, for the trip in September 09. These tickets were issued 11JAN09.
Should I have heard something from Amtrak if there was a change in the car numbers regarding my tickets, or am I correct in surmising that the car numbers at that time will correspond with what's printed on my tickets?
Based upon the reports of others, I suspect that your numbers have changed. However for a trip in September, it's probably still a bit early for Amtrak to have reached people with reservations for that month who were affected by the changes. If there have been changes though, then yes, you should be getting a phone call from Amtrak.
Did you book the trip online? If so, see if you can still view the reservation, although based upon reports from others you probably cannot. But still worth a try to see what it says. If you can't view it online, then you'll either have to wait for Amtrak to call you or call them to find out where things stand.