I have a couple like that, Accepted on 3/30 and 3/31...stuck in processing. 

I called the PPS on Thursday all they could tell me is that it was "in review"....neither of them have anything that would make me think they needed review...no refundable credits, no dependents, just basic straight forward returns (one is a single TP in her 20s with a W2, the other is single with a few retirement accounts and SS), very similar to the prior years, refunds are for withholding only...the PPS told me if the clients still don't see anything from IRS in 30 days to call back.