Kbolya1--Yes! You would have received confirmation emails if they were submitted. Check your spam folder. If it's not there, then I would get in touch with your letter writers right away and kindly ask them to submit your letter before the deadline tonight.
I submitted this morning (F1) and received 2 emails from grants.gov. The first says a tracking number has been assigned, and the second says the application has been validated and is being prepared for Grantor agency retrieval. I'm not sure if there's another one coming after this... I think if you've gotten both of those emails you're probably good. At least, I hope so! :-)