ANY major change in routine (positive, negative, neutral) is a stressor.
Now, I happen to be of the belief that it's good/vital to learn to deal with said changes, but I'm pretty biased. Both because I've been in school since my son was 2mo old (for the past 9 years part time), and because I love travel. If I was never willing to mix up my son's routines I'd never have been able to go to school (with a schedule that changes, often drastically, every 3 months), or send him to preschool, or take him travelling with me. All of which I find to be pretty valuable.
BUT every time things change out, it takes up to a few weeks to settle into a new routine. And there's fallout. When he was a baby, not so much, but he didn't know any better. After his first real 'independence phase' (at around age 3, we skipped the terrible 2s and had the terrible 3s instead) major transitions came along with expected fallout.
6 years later, he deals with change and transition pretty fluidly... but it's a learned behavior for him (no idea about children in general, although I suspect it's a learned behavior rather than an innate one). Thinking out how things are going to change, getting excited for certain aspects of them, being willing to be okay with the unknown, figuring out how to deal with the less than ideal aspects / find workarounds. ((I suspect it's a learned behavior, mainly because of how adults react to change. Just look at all the "OMG, how am I not going to go crazy this summer with the kids home?!?" posts, or how many people feel about moving, or all the HUGE ceremony aspects we place on major changes -weddings, births, funerals-, and tendency to add ceremony to most minor changes -big girl beds, potty training, kindergarten, graduations, boyfriends/girlfriends, etc.). We add ceremony because change is difficult for most people -including moi-. Whether it's a new haircut or new spouse, we seem to 'startle' pretty easily as a species. Shrugs.)) ANYHOW. For kids, it all counts as stressors.
You and hubby are now home full time, which completely changes the routine, and she's just had her bed changed. Either is enough, in my experience, for a bit of fallout.
If your daughter is like my son; she's just had 2