Does not seem to work for me ...
Please consider this sequence and region
chr11:75258534-75258583 in HG19
ttttcaaacttcagcctgcatcagaaacatctggagggcttggtaaaatc
This regions is repeat masked in hg19 FASTA file (lower case) and my blat output still says 0 for the repMatches.
A bit confused.