Yes and no.
A thermocouple makes a voltage based on the difference between the hot junction and where the thermocouple wire is mated to copper wires (the cold junction). Not an absolute temperature. Normally we measure the cold junction temp with a simple thermistor or just assume it to be like 75F, and infer an absolute temp of the measured temp from that.
If the wires are very short, the wires may be conducting heat off the hot junction. Taking a thermistor measurement next to the cold junction won't compensate for it, because the thermistor wire's metal itself is hotter than the ambient air around the cold junction.
Also if there is no cold junction compensation, a short thermocouple wire run may place the cold junction in a location which is heated by whatever hot area you're trying to measure. This makes the assumptions about ambient temp inaccurate.