Paper filed March 15th, no record of it

Hi, 

I sent out my taxes March 15th, because the e-file didn't work. My husband passed away in January, and from what I can see, that can cause a rejection due to errors on the IRS side. I then sent in my tax return, but they have no record of it. Is it possible that they have not gotten to it? Should I just send it in again? 

Thanks!