Maybe it was the approach of the Thanksgiving holiday, but the Denver Post and The Rocky both seemed to be caught flatfooted in their coverage of the narrow passage of Measure 1A this week. The local NBC television station, Channel 9, was way out ahead in getting reaction and analyzing what lies ahead. The measure will raise about $12 million through a local sales tax increase and the money will go for vouchers for preschool tuition, the amount to be determined by family income and the quality of the preschool the children attend