I can see a couple of tips on the margins curling ever so slightly up, very subtle but telling;
Without getting into too much gritty details. The thermal denaturation of the photosystem II (PSII) membrane protein complex.
High temperature stress can cause protein denaturation in plant leaves, disrupting cellular functions and leading to various detrimental effects on plant health. This denaturation occurs because high temperatures can break the weak bonds that hold proteins in their specific, functional shapes. Proteins, including enzymes essential for photosynthesis and other metabolic processes, have a specific three-dimensional structure crucial for their function. High temperatures can cause these proteins to vibrate vigorously, disrupting the weak bonds that maintain their shape, leading to denaturation. High temperatures can also disrupt the integrity of cell membranes, particularly those in chloroplasts (thylakoid membranes), which are vital for photosynthesis. This can lead to lipid peroxidation and further impair photosynthetic efficiency. Plants have evolved mechanisms to cope with heat stress, including the production of heat shock proteins (HSPs). HSPs act as molecular chaperones, helping to refold or stabilize denatured proteins, thus mitigating the effects of heat stress. However, if the heat stress is severe or prolonged, the plant's capacity to produce HSPs may be overwhelmed.
At some point during the leafs development, there was possibly a temp spike, enzymes denature, weakening the structure of the leaf, possibly causing mild deformity, temperatures drop, plant creates HSP's to correct and restore denatured enzymes. Battle scars of life! Battle on! Keep temps under 87F. Bad things happen. Certainly nothing to worry about so long as it doesn't progress or get worse over time.
Just a guess on my part, take from it what you will.