Rabbit not eating greens query

I usually give a handful of foraged greens (dandelion, plantain, groundsel etc) every morning and normally Buttons devours it at the speed of light. Yesterday, however, and today, he just hasn't been interested. Sure he's not poorly as on both occasions he's just jumped back into his basket and carried on eating his meadow hay. Then when I've topped up his bowl with his Excel birch bark in he can't get enough. Poops are normal. Just wondering as it's so out of character.

Could the forage be contaminated in some way ?

Oh hope not because other bun's eating it fine. it's from a little green space close by - no traffic, very few people. Dogs yes, but have washed everything. Will keep an eye on him and see what happens tonight . Might just stick with herbs tho' now you've put that thought in my head.