I bet you're using an Apache::Registry script with a global my variable.

my $t = time;
sub print_t { print("$t\n"); }
print_t();
print("$t\n");
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This is not a mod_perl problem, but an Apache::Registry problem. Apache::Registry puts your script in a function it executes every time the page is requested.

my $script = sub {

my $t = time;
sub print_t { print("$t\n"); }
print_t();
print("$t\n");

};

$script->();  # A page request
sleep(2);
$script->();  # A page request
[download]

the problem is that print_t closed over $t, so it always refers to $t original value, even though $t changes.

1175021938
1175021938
1175021938  <- print_t still references the original $t
1175021940
[download]

The fix is to use package variables instead of lexical variables for globals in Apache::Registry scripts.

my $script = sub {

our $t = time;
sub print_t { print("$t\n"); }
print_t();
print("$t\n");

};

$script->();  # A page request
sleep(2);
$script->();  # A page request
[download]

1175022050
1175022050
1175022052
1175022052
[download]