Newly back (again) and have a Steps Calorie Adjustment Question

Juliechilli

Happy New Year all, This morning I went to spin class and burned 353 calories according to my HRM. Now I am at work and not moving as much (desk job) and my calories have adjusted to 330. My question, why would I lose my initial workout calories? Wouldn't those be the calories I already burned during my working? I feel like I have to continue walking around the office to keep those initially burned calories. Thanks for any input.

Julie