Join Date: Feb 1999
Location: San Jose, California, USA
Programs: AS Plat, UA MM, AA MM, IC Plat, Marriott Gold, Hilton Gold, Hyatt Globalist
Posts: 3,162
IME, TripIt's Android app doesn't categorize trips as "Past Trips" until the following calendar day. Perhaps this period isn't long enough, but as SAT Lawyer describes, it's very easy to pull up past trips from the app, if one can be bothered to open the menu.
TripIt is far from perfect and has many design issues worth addressing, but this, IMHO, isn't one of these.