Do they go off their pellets?

I have two buns, a male and female. I had the male since he was 10 weeks and the female since she was about a year, have had her for around 6 months now. Anyway the male has always been on Excel junior, and I started her off on this when we bought her home. They loved their pellet time and got really excited when I go to feed them. Anyway normal routine They have half a treat, a papaya tablet and then their pellets, this has been the norm and hasn't changed.

Anyway since Christmas eve, she had a poorly tummy, stopped eating, rubs later she started eating again. But since this incident she hasn't been a huge pellet lover, she has her treats still eats her hay, Timothy being the favourite, yet pellet time comes and she has a few mouthfuls and then leaves.
I try her on another naturals treat just to check she doesn't have a poorly tummy, which she eats, she just isn't a lover of the pellets any more. I know the pellets aren't a huge thing, as long as the hay is being eaten, I was just wondering if I am missing something. I know they get some goodness from the pellets, so should I try a different variety with her to see if that helps, or am I worrying too much?
This has been going on for about 4 weeks now, some days she has more than others but no where like she used to before the tummy problem.
Any suggestions?

Maybe it's worth switching to the adult pellets instead of continuing with the junior ones. Or perhaps a different brand.

I'd get her teeth checked.

I think I am just being a paranoid momma, as just went to see them and she is busy munching away on the left overs. Maybe I feed them too early. I think I started feeding earlier when she had a bad tum so I would know if there was something up as early as poss. Maybe I need to feed a bit later. Its an hour earlier roughly than what I was doing, do you think that maybe an issue here? I think her teeth are fine as she eats her treats which some are harder I would say than pellets. Or maybe she just isn't a huge eater compared to the other, she is a smallish bun, maybe I over face her, they get an egg cup full each, this morning for instance she left half her spring green, but seems fine in herself maybe she is just fussy. I dunno :?