Mark on leaf

Things like this are often caused by wetting the leaves when watering. The water evaporates, leaving behind minerals salts that then cause the burning. It really isn't much to worry about, your plant will grow fine, just try and keep the foliage dry. Also, sometimes, plants just have funny leaves for no apparent reason, often with the first few especially, it is almost like the plant tries to work out its roots first, before concentrating on the leaf growth. Either way, it will not affect growth and remember too, no plant will ever have 100% perfect leaves, 100% of the time! Nice choice the Tropicanna Poison, she is a super sticky, delightfully smelling and delightfully tasting plant when ready, with thick chunky and dense flowers, just mind the humidity when close to being ready, the denseness can be mould attracting, but not a problem if thought through properly. Hope this helps,..... Organoman.