This is not a consistent drop and yes it is perfectly normal.
The first night was half a degree. The second night .3 degrees. And then you have 1.2 degrees -- this is your mark. At this point she will level off and then come back up and have the puppies. Usually, within 24 hours of this jump.
If you were checking twice a day, you would see a variance between day and night, like 101.2 M, 100.8 N; 101.0 M, 100.6 N; 100.9 M, 100.2N; 100.4 M, 99.6N; then it can get funny. 99.4 M, 98.7N; 98.5M, and then puppies are being born by that evening, and the temp hasn't been taken.
Usually they will hover around 98 - 99 for about 12 hours and then the puppies are born, usually after the temperature comes back up. We do not note the raising of the temp because we are busy with puppies.
I am expecting your puppies are probably on their way.
Heidi Ho, Odie
Joy-Joy, Bear Cub, Hepsi-Pepsi
Cujo2, Karma Chameleon
Ramona the Pest, Kojak -- who loves you baby?
Tiny Tinnie, Susie's Uzzi, Kaiah -- The Baby Monster.