My CEL is on... then it isn't!

2001 Toyota Solara V6 Auto. My CEL came on, and then disappeared, and did this a few times. It only seems to come on when it’s really cold out and the heater is on high.

Eventually it came on and scanned P1155, which is apparently “A/F Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)”

Is this something I should care about?

There is no cause for immediate alarm. One day the CEL will come on and stay on. Then you will need to replace the air-fuel O2 sensor.
Read more over here:

Given when the light comes on, it’s possible that there is simply a corroded connection at the sensor.