Please help (audio sample included)

I heard this at Shop Rite. This section is at the end of the song, a rhythm guitar keeps playing this riff, while a lead does a solo on top that mostly lays on one note tremolo picking. I honestly cant recall any lyrics or other melody. The rest of the song features an electric guitar doing island style chords with tremolo and delay.

I was once told it could be grateful dead off the Aoxomoxoa album, but upon checking it on itunes, didn't recognize it in the samples.

any help will be appreciated!

http://www.youtube.com/watch?v=OWBpRlZUDqk

so i spent a long time looking up grateful dead, steely dan, and santana songs. and none seemed to be it...

any suggestions? I honestly can't name a single lyric...

perhaps it's something jerry garcia solo? although i looked and looked and didn't find it