when you are the target

just received a package from the united states and put my detector on it. the thing goes off buzzing like crazy, I realized it must have been beta (radioactive) dust particles on the package – cardboard box, and it is hard to tell how it got there, was it on purpose or it just collected itself through the regular postal processing. the package traveled for way too long, it was sent out on march 17th (2019) and arrived today, april 22nd - wonder where it has been - the tracking on usps site says it is still traveling! i would have known more if my detector could read alpha radiation but it is limited to beta, gamma and x rays. the item inside looks okay, does not radiate, just the throwaway packaging (external surface) itself caused the higher readings and machine to go off. immediately regretted for taking package inside home without prior checking. i will forever wonder what were the prospects of radioactive contamination in that regard?