TC reported obstacle detected at Front DT car 'A1' door. Staff (BDL) confirmed train door opened andclosed normal. No obstructions was found. ~~~~~ 3614 TC reported obstacle detected at A1 door. Staff (BDL) confirmed train door opened and closed normal.  No obstructions was found.  Checked in depot for door obstacle (FOD) - N . Checked weather strip, door roller for wobbling - OK. Cleaned J-Rais as PM. Push-Pull door operation - OK. Door Cyclic test 20X - OKTIMs door static test - OK. Swapped DCP between 3614 A1(1412W02022ISO11) with B1(1412W02022IS033) for monitoring. Postulate FOD dislodged. Le JC 44880