not recognizing changes

I have a .txt file that's holding some log files generated by a php script. There is then another script that parses the logs and displays results. * This is what's really strange: when new logs are generated (meaning that the .txt file now has new lines with log data) the php parser is reading the old version. Only if I leave the script alone for a while (I haven't figured out how long) will it recognize the changes. * Gets stranger: When I ask: $unixtimestamp = filemtime ('logs/file.txt'); the time is marching forward, but some how something is cashing the content. This happens to be on a shared Unix machine at Hostway.com - and I'm working from the house with the lovely connection of AOL (yuck!). Thanks for any input, Sean