Brahms: Piano Concerto No. 2 in B flat major, Op. 83

Every year, I listen to the 22 LPs in Funk & Wagnalls' Family Library of Great Music.  Usually, I do this in May, but for lengthy and uninteresting reasons, this year I'm listening to them in June.  To-day, it was Brahms' Piano Concerto No. 2.  I've listened to this only a couple times, but this time I noticed something in the first movement.

Starting at about bar sixteen of the D section, there are octaves in the piano part:

(click on the image to enlarge it)
(notation found here)

I'm not sure if it's meant to, but it reminded me of the B-A-C-H motif.  Brahms has Ab G, E Db, and then Gb F.  It's like Bb A C B in that there are sequential descending half-steps.  I don't know very much about Brahms, and the resemblance here might just be a coincidence, but - if nothing else - it's given me a reason to become more familiar with the piece.