My cat hasn't used her little box all day today. Should I take her to the emergency vet?

We have had our cat - a rescue who ran up to us on the street, we tried to find her family with no luck and have now adopted her - for a week and a half. She's a tortoiseshell and about a year old. She has used the litter box with no problems for that whole time, right from day one. On Sunday we bought a bigger box with a cover (but a big opening so it's still pretty open to avoid trapping smells in there); she has been using this box with no problem at all. We keep the box religiously clean and usually scoop it out or check it every time we're in the bathroom. I cleaned it last night and the normal amount was in there. However, she hasn't used the box yet today. She's been eating (she had canned food this morning and has snacked on dry food throughout the day) and drinking, although I'm not sure what her water intake is. I cleaned the apartment quite thoroughly today and didn't find any mess outside of her box, although I know they can always find some little nook. It's also possible the cleaning freaked her out - it's the first time I've used the vacuum since we've had her, and the bathroom (where we have her box) smells like laundry detergent from clothes drying at the moment. However, she doesn't seem stressed or in any pain. I have not seen her attempt to use the box today; as far as I can tell she just hasn't been in it. Should I be worried? We have a 24 hour emergency vet nearby if necessary. Thanks!

Read more: My cat hasn't used her little box all day today. Should I take her to the emergency vet?