I believe it would more accurately be described as preignition, which is not the same as detonation although preignition can often lead to detonation.

It has been my observation that a glow engine that is too lean behaves a lot like a model diesel engine that is overcompressed and a spark ignition engine that has it's ignition timing over advanced. This leads me to think that we actually use mixture adjustment to fine tune the ignition timing of glow engines. Glow plug heat ranges and head gasket thickness is used to make course adjustments in ignition timing but the mixture fine tunes it. If you take a Cox .049 engine and add several head gaskets to lower the compression, you will find that the engine wants a leaner mixture for peak power.