Hello!

I have a few lemon trees that have been planted from seed, about 5 months old. I have just started to notice some light brown patches around the stem near where leaves have grown. At first I thought this was just the outer layer of the stem becoming more like bark, but then I noticed a strange formation on one of the leaves that was the same brown colour. The leaf also has an indentation where the discolouration is occurring. Could this be CLM? It is just a straight deep line with a small circle beside it... I will attach close up photos. As far as the dicolouration on the main stem, it is very isolated, only on two of the six trees... Should I be concerned? Any advice is greatly appreciated.

Thank you!