I e-filed my taxes 5 days ago and it still has not been accepted. Could there be a problem?

I e-filed my taxes on Jan. 12th. I know they didn't begin processing them until the 14th, but they say it should take 24-48 hours to accept your e-file. It's now into the 5th day since they began processing and my e-file is still pending. I've never had to wait this long for them to accept my e-file before. Could there be a problem or is the IRS just really backlogged this year from everyone e-filing at once when the gates opened on the 14th? Is anyone else still waiting for theirs to be accepted after this long? Thanks in advance for any help.