Usually not necessary assuming you will be feeding the same RPTV input at the same scan rate (480i or 480p) as before; but a good idea anyway. Not all players will produce a signal that plays by all the rules. Sometimes the user controls need a little tweaking.
It's also possible that the RPTV itself has drifted slightly out of calibration. If you had your set professionally calibrated the tech may be willing to come back out for a followup cal at nominal charge.
Technically, the answer is absolutely. No two DVD players will output the exact same quality of signal, and thus the TV should be recalibrated. How much of a difference is there? Probably not a lot - but there still is a difference.