Simply put - he sold you a little tiny bit of shitty weed mixed in with sage.

No one pre-grinds weed unless they're up to something shady.

This brings me back to the time I was offered a full ounce for $70. Still being quite naive, I decided to have a look at it. It looked like your sage-weed but even more brown and with large twig like stems mixed throughout. I did what anyone should do in that situation and told them to go fuck themselves.

Little tip: next time you buy weed, look at it and ask yourself, "Do I need someone else to tell me whether this is bud or not?" If you do... don't buy it.