So, Oswald, before leaving for Mexico City, and then, supposedly, Cuba and, eventually, the USSSR, perhaps permanently, takes the time to arrange for someone to return his library books, on time, because..he is worried about library fines, and/or charges for book replacement?
Ok.
Or, maybe, the whole Mexico City trip is just a theater piece, designed to make the Cubans, Soviets, CIA ( gee guys, you didn't notice LHO during his 3 visits to those embassies?) all go into " Incoming! CYA " mode?
Note: Above is conjecture; CYA is " cover your a#@".