I had a similar issue where I left my iPad on the seat getting off of an AMS-MSP flight. Whenever I boarded my next flight to AUS I realized it was missing and informed the gate agent. They sent a redcoat who found the iPad on my previous flight however they could not get it to me before our flight had to leave (and I was unable to wait for a later flight). The gate agent said they would mark it and if I put in a claim in the lost and found service they would get it back to me. The MSP baggage office called me the next day however I missed the call and no voicemail was left. When I managed to get back in touch with them a few hours later they said the iPad had already been sent to the Lost & Found central processing facility in Georgia and they would get it back to me through the lost and found system.

That was a month ago and after two lost and found submissions and several calls no one seems to have any idea where my iPad is. No communication at all from the lost and found service and absolutely no way to contact them. I understand that I lost it and that is my fault, however it is also hard to understand how Delta managed to find my iPad and then subsequently lose it. A very frustrating experience with Delta's lost and found (outsourced) service. I hope you have much better luck than I have had.