You may want to have a look at this post Re^2: Grab 3 lines before and 2 after each regex hit (sliding window).

The update shows a generic solution how to parse a sliding window of 6 lines and test the 4th one.

use strict; 
use warnings; 
use Data::Dump; 

my @window; 
while ( my $line = <DATA> ) { 
    push @window, $line; 
    next if @window < 6; # init 
    if( $window[3] =~ m/[^\d]+\d+/ ){ 
         dd \@window; 
    } 
    shift @window; 
}
[download]

You could easily adapt this to your needs.