He probably perked up because it was a relief to know you wouldn't be in need of rescue services, and thus not be a burden ($-wise) to the agency.
I had a similar conversation with a Maricopa Sheriff's Deputy at First Water TH yesterday... we went through the litany of:
Do you have plenty of water?
More than enough in the bladder along with two extra 'emergency' bottles
Where are you hiking?
Second Water Trail to Boulder Canyon area
Are you going all the way to Canyon Lake?
Nope, just to the Indian Paint mine area where I'll recon and/or climb a peak just south of Battleship then another just west of it. (He didn't seem happy I would be 'off-trail')
Do you have a map?
I don't need one... I know the area well and I have a GPS.
A cell phone GPS or a true GPS?
I see you are hiking alone, do you have a SPOT?
No. (I'll skip that debate which simply wasted 5 minutes of my hiking time.) Besides, I left a detailed itinerary at home including the trails I planned to hike, potential off-trail routes along with key way points.
Well you know, there were three men in 2010 who went missing on the hottest day of July... blah,blah, blah
(Another 5 minutes wasted)
Yeah, I know all about them, I spent many hikes searching for them, and in fact I was on Yellow Peak (where two of the three were found in January 2011) on two occasions, once seven days before and a second time two days before they were found. As it turned out on my second trip I had come within a 100 yards of the spot there were found. So yes, I do know the area as well as the hazards.
Watch out for rattlesnakes
(Another 5-minutes wasted... before he seemed to get I knew more about rattlers than he did)
Well, if you get airlifted to Good Sam for a rattlesnake bite you're going to be starting at $100,000 blah,blah, blah...
Well, be sure to fill out the log before you go.
Whew! After a 20 minute exercise in futility I could finally get started on my hike.
I fairness... due to how many stupid people he & I have both seen or heard about, I fully understand his concern.
However, in this case it was pretty obvious I wasn't dressed in shorts & tank top with flip-flops holding one half-empty 16 oz bottle of water and planning to hike ten miles 'over that way somewhere'.