Squee.
I ran into a similar situation, I sold somthing on eBay to an Oxford professor. I'd used several of her pubilshed works through my degree, and I have to admit I seriously considered enclosing a note. N the end I didn't, partially because I wad selling old maternity clothes, which for some reason seems a personal purchase, and partially because it seem alittle weird, however hhad she been an author instead of an academic I probably wouldn't have wussed out of including it.