You are almost certainly seeing fluorescence here. Even 532nm is still a fairly short wavelength as far as fluorophores are concerned and many fluorophores commonly used to color plastics absorb powerfully at 532nm. For example, rhodamine B has an absorption peak near 532nm, and it fluoresces strongly in red yellow. Indeed, if you see the Wikipedia Page for Rhodamine B there is a picture of a 532nm laser lighting a rhodamine B solution, and the red/ orange/yellow fluorescence gives an effect almost identical to what you are seeing.
You are almost certainly seeing yellow/orange/red fluorescence mixed with scattered 532nm light.
This doesn't prove that rhodamine B is in the plastic - I know nothing about whether it could survive the production processes for plastic (I suspect it would not) - but the point is that there are many fluorophores that would show exactly the kind of behavior you are seeing.