ASR Approach - Doing the Controller a Favor

I was asked if I would accept an ASR approach into a satellite airport
for controller training. I said, sure no problem. I got a wide
vector that put me on a 15 mile final. The controller gave me a "10
miles from airport, complete pre-landing checklist". I've never heard
that one before - it was a military radar facility.

Anyway, I reported the airport in sight about 8 miles out and the
controller terminated me and gave me the standard "squawk VFR,
frequency change approved".

My question is: Should I have waited to report "airport in sight"?
The tone in the controllers voice gave me the impression that I
somewhat ruined the training for the rookie by reporting the airport
for far out. I was 8 miles out at 1500, the mins were 440 feet and
one mile from the runway.

In hindsight, I wish I would have asked the controller if they wanted
to continue the ASR to mins. Is "airport in sight" the magic phrase
that cue the controller to let me go?

Thanks

Chris
Mooney N9373M