[Githmig]

Wonder about the truck though, if it was indeed a police vehicle, how exactly would the OP know that? I mean...don't they have to be marked as such? I mean, if you thought someone was watching you, you'd get suspicious too wouldn't you? I mean, it's understandable if say, the OP changed route if it had been a police vehicle in the first place that stopped to observe, but otherwise it seems, as Genderhazard noted it's just a case of it being early hours: Be suspicious of everything. There's nothing wrong with being safe is there?

As for the actual encounter with the Officer, though it pains me to agree. If you can't stay polite stay silent. Comply. Answer questions quickly and as succinctly as you can. If this is not an officer you know from the area, don't try and engage in small talk, especially if you feel it can be misconstrued.