What the radiologist is getting at here is that it would be surprising if such an opacity had arisen so soon after the previous film available for interpretation. He/she suspects that it may be a coincidence of the alignment of normal anatomical structures on this particular film.

See reference. [points to: Delrue et al. Difficulties in the interpretation of chest radiography. in: E.E. Coche et al. (eds.), Comparative Interpretation of CT and Standard Radiography of the Chest, 27 Medical Radiology, DOI: 10.1007/978-3-540-79942-9_2, © Springer-Verlag Berlin Heidelberg 2011]