Radar contact before squawk

I learned something Friday night while getting in some night solo time. I
called Whidbey Approach for a few minutes of flight following and possibly
clipping their Class C, and the controller annonced radar contact, and then
issued a squawk. I hadn't given my position (I wasn't too sure where I was
anyway :-) ). He apparently didn't find it necessary to talk to me after I
popped up with the discrete code.

I was probably the only VFR target in his entire airspace, so there was no
ambiguity. Still, question for the controllers, is it standard procedure to
announce radar contact to an untagged target?

-- David Brooks