I think it happens fairly often.
During recovery you probably used that L side more and maybe after still subconsciously protecting the R side..

And with the R side feeling so much better , then you would notice any L side sx more as you know what they are.


There are probably old posts mentioning this if I recall..

Did you have a specific cause for your TOS?
That you can think of?
Like some previous trauma, broken bone, large bone/ligaments?