Well that's certainly one of those memories you treasure. I put it up, because I've been looking at various musicians takes on what he does in that song (and other stuff). Hence you have to know your pentatonic scales and root notes blah blah. Trouble is my brain is bit like a fret board, I have to learn it in chunks then eventually put it all together in my brain like a jigsaw, it works honest lol. Complicated way of learning, but it makes sense to me, and it's not necessarily in chronological order either, because I have to keep my brain stimulated otherwise it won't process the information it's being taught.
My father in law spent years in blues bands, opening for a lot of the big names, only talking to him about it last Friday, BB King was one he never got to see. We watched about 2 hours of videos he has, of all the greats, explaining all the styles and why they used certain guitars for certain songs, have to admit most of it went over my head but it's great to see his enthusiasm talking about it.
Sometimes as with any music it can be boring in sections. Which is one of the parts I enjoy messing about it. If you was to look on youtube for lessons on that song, you would find literally dozens of interpretations of it. I generally will go through and look for someone who does it a little different to take out the bits where I might say, nah don't like that. Even B.B King didn't follow the original version in latter performances.