Yes, unfortunately it is normal but frustrating. Short sales are challenging and each one is unique because each lender follows their own rules. Patience is a virtue but if you're hoping to close this by 4/30 to capture a first time or repeat buyer tax credit....you may be disappointed.
If the house is phenomenal and you want it no matter what then patience is recommended. If you're looking to capture to credit...keep looking around while this is in process knowing that you can withdraw your offer if something better comes along. (depending on how your offer/P&S was drawn). Legal counsel is always advised.