when i make a post, wordpress automatically numbers it ?ag=1. so then i link to it on twitter or tumblr with a picture. then a few days go by and i make another post which now has that same link. so if somebody goes to the first pic and follows the link, it won't go to that post, but the most recent post. should i be doing something about this. if so, how do i fix this? is there a permanent numbering system i should be using or something?