Public place means yes.
I am sure there would have most likely been a heap of cameras on you the whole time you were in the store as well. The only reason he probably followed you out was to get a pick linking you to the car for ID reasons later.
IE - there is no point having a photo of someone if you don't have a name to connect it to. Now they have a photo, and a car to tie you to. This is no way an accusation of guilt or proof you did anything, just that something you did may have stood out as suspicious (for instance they may have only seen you putting the items back in your bag) but not sufficient enough for them to stop you for suspected shop stealing. They can then review their footage, see if you stole anything and if it was shown that you probably did, they then have a car rego to tie your picture to, giving Police a way to track you down. If you didn't do anything, you won't hear from them again.
Go anywhere near a casino, airport, court house, and most shopping malls and you are going to be filmed countless times....hell, the entire last city I worked in was covered in cameras all through the main CBD area, local parks, skate parks, roads, shops....everywhere.
"He didn't want to tell the cop he was on his way to the Butt Pirate Palace for a little two-step with Joe-Joe during the Village People marathon." - Cat_Doc
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You can't flip it over and start again...Don't blink..." Kenny Chesney
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