Toby does the same thing with some foods!!
The other day I handed him a baby carrot...he took one bite & threw it on the floor, then laughed. He normally loves his carrots so maybe he just wasn't "in the mood" for carrots!!
He usually loves veggies but some days he might completely ignore them (or throw them on the floor!!) and the same with his other fruits. About the only thing he will eat ALL the time is nuts & sweet taters.
I change his food around alot to give him a good variety. Fresh foods can make a big difference in their feathers and of course their health.
I'm not sure about tiels but I know with macaws they shouldn't be on an all seed diet. They need to be offered a variety of food.
I offer pellets in Toby's seed mix but he doesn't really like them. He may eat one now & then but mostly just throws them out. Some people feed an all pellet diet though...and I know you shouldn't offer vitamins if they are on that kind of diet because the pellets already contain vitamins.
Sharon & I have discussed giving our fids vitamins for awhile...and I've been giving Toby vitamins in his water for the last couple of weeks. I was just wondering how many people offer vitamins.
BTW, we need updated pics of your tiel Laurie!!