Honestly I would be a bit concerned. Firstly because generally not being able to control herself around treats is highly unusual. My 7yo (with ADHD) and my 4yo would and do leave food untouched if we say no more, that's enough for today. We wouldn't need to hide them. They are physically able to access all the crisps, biscuits, yoghurts, ice lollies etc in the house but they don't sit and eat them all. They ignore them most of the time and then ask for them at times when it seems appropriate to them, and accept the answer given (though they might plead or whine a bit if we say no).
At 7, she ought to be able to resist temptation, especially when a, she's already had some and b, it's out of sight. It's not at all the same as leaving a plate of biscuits/bowl of sweets etc out in the open and expecting her not to have any at all, or giving her a big bag of crisps and asking her to only eat half. Or e.g. her being at a party buffet and having more than her fair share of something. Those are more normal things it wouldn't be fair to be cross about.
Going out of her way to "look everywhere" for them is really unusual, unless it's a behaviour you've almost sort of encouraged accidentally?
I am just thinking - my eldest (now a teenager) used to be so persistent about having more of foods that I did literally used to hide things from him, partly because he was so insistent and I didn't know how else to stop him asking but partly because I was absolutely crap at holding any boundaries (I was a young parent). I have a better understanding now and see that hiding things and saying they were all gone was not holding a boundary, it was just lying to him and avoiding setting the boundary. He never really twigged about me hiding stuff but if he had come across it and been like "Look Mummy I found some more, they aren't all gone!" then he would have genuinely felt he was in the right, and I probably couldn't really blame him for that. However if your DD knows you've put them away because they're all done for today, but she's gone seeking them out on purpose in order to eat them, that feels a bit sneaky and like she's going against what you've said, which is not really on.
I did get a bit cross at DS1 later on at some point when he would finish things without considering whether anyone else would like more of them, but to be fair to him since then he's always asked and been considerate of this - I think it had genuinely not really occurred to him before. I do sometimes bury things like the spicy breaded chicken breasts in the freezer so he doesn't notice straight away that we have them otherwise he will inhale several at once and nobody else gets a chance. But things like that are pretty much considered fair game so it's not especially wrong of him to want to eat them.
Out of all 3 DC, DS1 would eat entire packets of things like sweets/biscuits in one go, he doesn't have an off switch and won't self-regulate, although other foods he has never had much of an appetite for at least until his teens. He also has ADHD. However he doesn't touch things belonging to other people or which are "communal", and wouldn't have at age 7.
DS2 does have a point where he will stop and put the rest away for another day, even for his own sweets, and is a stickler for rules so we could have told him not to eat something from about age 2 and he would have followed it (he is probably AuDHD TBF, rather than purely ADHD). But he has no patience so if he thought that something rightfully belonged to him and he wanted it, he would have it as soon as he wanted it rather than wait according to the rule set by somebody else.
DS3 goes through phases where he eats everything in sight and in general really seems to gain much more enjoyment from all kinds of food than the other two, but he will also stop when asked to, and if they have something like an Easter egg each, he will eat more of his than DS2 but he will also follow DS2's example and ask us to wrap the rest up and store in fridge.