I see what you mean. To really be considered comic relief, there needs to be a generally lighthearted feeling and/or a change in tone.

I do think the landlord's grovelling can be called comic relief. I would also argue that Pentangelli's performance at the Communion (drinking from the hose, "can o' peas," Pop Goes the Weasel) can fall into this category.

I also do not believe that every good drama needs comic relief. For instance, I consider "Silence of the Lambs" to be on a par with GF and GFII, and it was uniformly grim.