no, I distinctly remember the very large mileage, not the distance to Tucumcari.
the sign may have been button copy and I wasn't paying attention. the other thing I remember from that trip (other than the rain/snow mix) was that some of the "temporary" ranch connections on I-40 had not yet been closed off.
looks like the original thousand-mile sign vanished sometime between January and July, 2005. Quite a shame. I wonder if the "1007" miles even reflected interstate mileage.
a quick Google Maps search reveals the distance along I-40, I-15, I-210, and CA-110 from the TX/NM state line to the Four-Level Interchange to be precisely 1000 miles.