What could cause a swollen lymph gland in the mornings?

Many causes: Enlargememt of the lymphnodes can be anything from infections to allergies to malignancy you need a full history and phsical along with labs and a chest xray.

Monitoring Centers: Lymphatic system absorbs/carries things too big to go into the arteries/veins like bacteria eaten by white cells and digested food. Lymph nodes "taste" the lymph for anything bad like bacteria/viruses/cancers, etc. When it detects a problem, it alerts the immune system and your body reacts. They enlarge in response to the inflammation they create when they react. They shrink when all is well.