went back to NorCal and cancelled IFR, [...]
When I reported back on the [practice] missed at Tracy
and requested flight following back to Hayward (KHWD)
I was asked to cancel IFR.

Maybe they didn't receive your original cancellation. Either NorCal
didn't really cancel, or they didn't transmit the cancellation properly
(would Tracy have advance strips on you?)

Jose
--
The monkey turns the crank and thinks he's making the music.
for Email, make the obvious change in the address.