flirting or stalking

Not sure what to think about this…

I went for my usual jog with Dexter today. Ever since I found the nearby park where dog leashes are optional and the trail is just about a mile long I’ve taken Dexter there almost every night. In just two weeks I’ve shaved over 40 seconds off my mile time from the first time I ran. Also, the daylight lasts longer every day and the weather has been holding out (dry and bright) so I’ve gotten to play fetch with Dexter after the run (his favorite part).
Anyhow… today I was approached in the park while I was playing with Dex. A man who looked to be late 20’s said hello to me from the trail and approached me out in the grass as the sun was starting to go down. He was probably over 6 feet tall, very dark, and spoke with a thick (non-British) accent. In retrospect, he was very nice. Asked me my name…told me he’d seen me running with Dexter around the neighborhood… told me his profession (electrical engineer)… smiled a lot… and showed interest in me which I suppose was no more than an average guy in a bar.
I know I’ve said before I don’t like meeting guys in bars… it just seems sleazy. Meeting a guy in a park seems like such a nice “how we met” story… so wholesome and “middle America”. So why was I so instantly judgemental and on edge?

He noted I wasn’t wearing a ring and asked me my marital status…to which I lied and said I was living with my boyfriend.
He asked me for my number… to which I replied my ‘boyfriend’ would really dislike that so I had better not.
He asked me if I would like to walk for a little bit with him… to which I lied and said I was already headed home.

I suppose if I was a guy trying to hit on a girl in a ‘non-threatening’ way, I probably would have employed the same tactics… but I (as the girl) wasn’t having it.
So what is it? Is it a classic case of a woman saying she wants something until it’s actually put in front of her?
Did I judge him based purely on how physically intimidating he was?

OR, was it my sixth sense telling me that something about the situation wasn’t right and I should bail out (better safe than sorry)?

Either way, I’m not sure what to do about my favorite jogging spot now. He said he lives on the same street as me (and even named the street) and part of me is nervous that he knows that and is watching me… BUT part of me thinks I’m just being paranoid and he’s just a guy trying to hit on a girl he’s seen jogging in the park.

Ugh.