Opening a file created on a pirated version with legal SOLIDWORKS

Hello, 
We are a small company in Portugal that has a total of 5 local licenses that we use daily for work. 

We receive files from clients we work with every day and this is what prompted my desire to ask my question to find out if we have reason to worry or not. 

If we receive a client file that was created on a pirated copy of the program (of course we have no way of knowing this) and open it through our licensed SOLIDWORKS installations, are we in violation of the license rules? 

Logically speaking, the answer should be a categorical no, since it is completely impossible for us to know what program the file was generated with and whether it is pirated or not, but I would still like to hear your answers. Thank you!