turtles and tortoises aren't really "pregnant," they're gravid. And the eggs inside the tortoise don't really get calcium deposited on them until the tortoise is ready to lay them.
I have heard, don't know if its true, that a female is born with as many follicles as she's ever going to have during her whole life span.
Now if a tortoise is egg bound, that's a whole other box of tissue!
If she is literally about to lay them and starts to hibernate, that would be an issue. However, something tells me that her instincts would tell her to lay the eggs before she begins to hibernate.
Generally fine unless she has already been retaining them for far too long due to stress. It would not be a major worry for me unless there was a known egg-binding history for the individual animal involved.