No, i won't agree. Your site indexes too fast mainly with the signature placed in DP. It's not because of the reason as you mentioned.
Hey, This tips are quite good. They can really do help your site gets indexed faster. Thanks for sharing these tips with us. Keep them coming.
Could be another way, but Google usually index newly created websites even if there is no backlinks at all... TIP: Just browse your website using any web browser with Google Toolbar installed and bang Even though the link from your signature is quite enough for indexing