Do I need to file an extention?

It depends.  If you are due a refund, an extension might not be needed.  If you owe money, you will be charged interest on the money you owe.

I am due a refund, but I filed an extention because I couldn't e-file and it was too late to get it postmarked as 4/15 because it was after the post office closed. Is that okay?

If you are getting a refund, there is not a penalty for filing past the deadline.

Just found the answer, thanks for confirming though