You know your BP better than we do, so if you think she's acting differently, that's fine.
I tend to think the simplest reasons are more often the cause of things rather than less likely scenarios. I think it's probably a temp issue. If it's 76.4F where she is now, and she's staying there, and it's 84-90FG in the rest of the tank, she just wants to cool down.
Am I 100% sure. No. However, that's a simple answer to a likely simple cause.
I would adjust your temps, as mentioned earlier, and if she still stays there, maybe something else is up. However, my BP, spends most of her time on the cooler side of the tank. Her range is about 77-89F with a gradient. Hot side being 89F and cool side being about 77F. I would be more concerned if she was spending a lot of time on the hot side.