Don't worry about it. It's normal in this case as there might be calcified structure called
'tartar ' which was accumulated causing the mobility and now that is removed from the teeth internally by the professional cleaning process called 'Scaling'.
Allow time to heal the gums on its own .also, dentist / periodontist might have prescribed some gel to be applied to the gums for the same.
For healing requires few days to few weeks
Next Steps
Gargle with lukewarm salt water after every meals to maintain oral hygiene
Health Tips
-Don't touch with the tongue to the teeth .
-Eat lots vitaminC rich fruits like aawla, oranges, strawberry etc.
-Maintain oral hygiene by following proper brushing technique as instructed by the dentist /periodontist.