Hello,
Yes, it’s google font, you can download it here http://prntscr.com/omldkk
We have tried everything. Problem appears only with the default Oswald light(300) or Oswald extra-light(200) in theme options, you may try by yourself – change either font or font-weight to 400 instead of 300 for example and you’ll see.
We found reports about similar problems while googling the issue but any solution for this or explanation what could be the reason of the problem.
Regards