Products of substitution reaction of alkane and halogen

As I have just finished my final examination in this school year, this is also another question I got the answer incorrect, according to the model answer.

The question is about the substitution reaction of methane and bromine in 1,1,1-trichloroethane solution. It is a simple one, how many organic products could be obtained from this reaction in maximum?

As I know, it is a reversible reaction, that is, for instance, methane could react with bromine to form chloromethane and hydrogen bromine, and vice versa. Hence I think if I consider methane also as a product would not be incorrect, and as a consequence, I got the answer five, namely, chloromethane, dichloromethane, trichloromethane, tetrachloromethane, and also methane.

After that, I ask my teacher about this, while he insisted that methane is not a product but an unreacted chemical/reactant. However, as explained above, methane found at the end of the reaction actually has participated in reaction, and it is formed as a product of the reversible reaction.

So any misconception here? I am not quite satisfied with my teacher's answer after all. Could anybody help? Thanks.