You don't need to resubmit the request. There are two problems with forwarding mail.
First of all, mail addressed to you at your former location will still go to your former letter carrier to deliver. He no longer marks it for delivery at your new address -- they haven't done it that way for years. Instead, he sends it to the regional forwarding site, a computerized operation that generates the sticker with your new address. It is then directed to your new post office for delivery.
It can take a few days for them to get your info into the system.
The other problem is that your letter carrier works five days a week. The post office delivers mail six days a week. Your carrier also takes vacations, sick days, court leave, etc. So some of the time, a replacement will be delivering mail on a route, not the regular carrier.
The replacement may not know you've moved. He just goes by the (old) address on the mail. Since many replacements rotate among a limited number of routes, yours will probably figure out you aren't there soon enough, and also begin sending your mail to the forwarding site.
Your best protection against the vagaries of forwarding is to notify your correspondents of your new address. The sooner they start sending your mail to the right place, the easier for everyone involved.
