CynicalEngine - 12:03 pm on Jan 30, 2012 (gmt 0)

What I've observed is that Google has been doing that for quite some time now (about 8-10 months), where its actually trying to rank an internal (more relevant) page for a term in spite of the fact that the homepage may have more authority for it (through on-page and off-page presence). However, since the inner page may not be as authoritative (link juice, number of links etc), it automatically falls down the SERPs for that given term.