When you cleaned the tank and put in new water, did you add anything to remove the chloramine/chlorine in the water?
Is it possible she's reacting untreated water.
If you have carbon in your filter, that should break down chloramine in the water, but that will take some time. Municipal water treatment used to use chlorine as an additive to kill bacteria. Most now use chloramines because it doesn't break down. However, that not breaking down part can be a problem for aquariums.
Chloramines can be deadly for fish and the bacteria growing in your filter. They aren't going to kill a turtle, but may irritate it.
It can be neutralized via water additives. However, many here, including myself, don't believe in dumping lots of chemicals in a turtle tank.
VeipaCray has a great thread on an aquarium water changing system that will neutralize the chloramine without chemicals:
viewtopic.php?f=9&t=33171Carbon in a canister filter will work as well. Once you have an established aquarium, with enough beneficial bacteria to keep up with the waste, partial water changes and carbon in the filter should be more than enough to deal with the chloramine in added water.
I'm not sure this is the explanation, but if everything else looks good and she's back to normal in a bit, it may be the answer.
The water temp sounds good. Turtles can bask quite a bit. But sleeping outside of the water could be a sign of concern.
I've not seen a gravid turtle myself, but one of the signs is trying to dig with her rear claws.