linecache and glob

[jo3c]

i have a 2000 files with header and data
i need to get the date information from the header
then insert it into my database
i am doing it in batch so i use glob.glob('/mydata/*/*/*.txt')
to get the date on line 4 in the txt file i use
linecache.getline('/mydata/myfile.txt/, 4)

but if i use
linecache.getline('glob.glob('/mydata/*/*/*.txt', 4) won't work

i am running out of ideas

thanks in advance for any help

jo3c