I wouldn't assume that recent trip has triggered her signs, since we'd have expected those behaviors when you were away. As well, I am glad to hear that that is her normal gum color (since pale/white gums can be a sign if internal bleeding --though this wasn't something that really fits with her vague signs).
Now the reason for my range of questions is because Brown isn't giving you many specific clues to what is amiss. Her withdrawal from you is a non-specific sign that something is wrong but what that is. Withdrawal is a behaviour triggered by instinct, where the agitated or unwell pack member keeps a distance to prevent putting the pack at risk of predators +/- avoid any bullying. So, the bulk of her signs are vague and only tells that she feels that something isn't right.
Now the reason I asked about her mammary development and spay status isn't because pregnancy is a worry. Instead, we can see dogs be restless, withdrawn, nest, and mother toys when they are developing a false pregnancy. And in many of those cases, they will develop milk. So, we do need to keep an eye on that especially if carrying that toy around isn't the normal for her. And I would just note that false pregnancies do usually settle on their own or there are hormonal treatments her vet can dispense if we do see this progress and she were to have milk.
With all this in mind, we do need to keep a close eye on her. None of her signs suggest an emergency issue but we want to make sure she doesn't develop any of those signs we discussed before. In the meantime, you can try her on a light diet (ie rice with boiled chicken, cottage cheese, white fish or scramble egg) to just offset any GI upset here since it is so common to cause them to feel unwell. As well, we could consider using a de-stressing treatment (ie Adaptil, Kalmaid, Zylkene, Bachs Rescue Remedy for Pets) to allay any anxiety triggering this. If we try these and she settles we are happy. Though if she doesn't or develops some of those signs I noted, then we may need to consider having a full check up to just make sure there is nothing brewing that Brown is struggling to tell us about.
Please take care,