I was in the Houston area last week and stopped at the Sam Houston Greyhound track to get their latest reward card. When I got home I noticed that the last card I got from them in January had a small "11" printed on the top right reverse, just above the mag stripe. The newer card that I got last week has "05" printed there. I tried to find out what the numbers meant but the person at the desk while I was there didn't know.

I was wondering if anyone in the area could see if they could find out anything about those numbers and if they could look for other cards with different numbers on the reverse to see what exists, etc. If there are other variations, I'd really appreciate any other cards for my collection if someone wants to trade or sell them.

Any help would be appreciated.