The only imperfection in the Mass is our un-love, our distractions, our interior complaints, our self focus..our lack of love.

St Paul's words are useful.

"Now I rejoice in my sufferings for your sake, and in my flesh I am filling up what is lacking* in the afflictions of Christ on behalf of his body, which is the church" (Col, 1-24).

what could be lacking (imperfect)?  

My Yes, My love, My Serviam. 

Do we rejoice in our [let's face it, minor] sufferings?