Non ideal behavior from single-supply rrio op amps
Neither one of the op-amps is rail-to-rail input. The MCP601 is only guaranteed to Vdd - 1.2V = 2V, the TLC271CP only typically to about 2.2V with a 3.2V supply, so it's entirely expected behavior for a voltage-follower connected op-amp. 

Edit: Here is the caveat in the MCP601 datasheet: 



The TLC271CP is not specified for 3V supply (5V and 10V), but there is a "typical" graph in the datasheet as so: 



From the below guaranteed specs at 5V (over temperature), and the typical curve, we might judge it's sort-of guaranteed to be good to Vdd - 1.5V or so at 3V, so 1.5V, but it's good to leave a bit more room on top of that, since it's not a guaranteed number.

Note: It might change a bit with the bias mode too, I didn't look at that carefully, since the problem was identified, but you should if it's a real design.