As Whistle Stop alluded, this is apparently a device Santana has added to his repertoire fairly recently. On his *Live In South America* CD, Sacred Fire, he does this quite often during solos on some of his older tunes, almost as if he were amusing himself. I heard the little half-step melody run to *Paint It Black* by the Rolling Stones in the middle of one of his solos, parenthetically placed in such a way there was no mistaking it was intentional, as if he were trying to make it so obvious the audience couldn't help catching the allusion. The result was it sounded awkward and gimmicky.

Compare and contrast to a tune on Chick Corea's Akoustic Band's CD, Alive. Chick plays a couple of bars of the song the Scarecrow sang in The Wizard Of Oz (If I only had a brain, etc....), woven deftly into the melody as an afterthought, like the lingering fragrance of a beautiful woman after she's left the room.