Op Amp Question

I wired up a 741 op amp as a voltage follower and connected Vin (V+) to a pot. I swept the sweeper to 5V and ground but read 4.93V and 1.92V respectively. Being a mechanical engineer, my first thought was hysteresis in the pot (that would be a pretty shotty pot with nearly a 2V error), but I connected the pot straight to the arduino and got the expected values.

Being nearly ignorant of electrical engineering beyond Kirchhoff's and Ohm's laws, why does the op amp not produce the expected Vin = Vout?

A 741 op amp is an old fart that can't swing it's output from rail to rail voltage. There are newer and better devices around for DC circuits.