After you file

I honestly haven't look at the return in depth, I just noticed when I opened the program in August (eFile was originally done back in late March or early April) the refund amount it listed was significantly higher.  I clicked through the error checker and it said everything was good so I am a little confused.  Other than going line by line with my filed return and what it is computing now and see what changed, how else can I figure out the reason?