I bought this Dendrobium Berry Oda a few years ago and she turned out to be a really vigorous plant (2 to 4 new canes per growth cycle is normal for her). But recently I noticed red spotting on her leaves. The spots seem to appear only on her oldest growths (the ones she had, before I got her) and honestly I don't even remember if those leaves always looked like this and I just recently noticed it or if it's something that spreads around. She isn't actively growing at the moment so I can't make any comparisons to the last few years but she was (still kinda is) in bloom and the flowers were as abundant as ever and did not show any signs of sickness.
The spots are not bumpy or anything and she has them on the upper and underside of the leaves, although they don't seem to correlate (different patterns on both sides)
I know it's normal for this orchid to have some red spots (mostly on the leaf tips) and that leaves can turn red to get protection from the sun, but here spring is just starting so it can't be because she received too much sunlight... Also as I said, her newer canes don't have the spotting (yet).
Honestly, I don't even know if it's something to worry about but I still wanted to ask (maybe just to ease my mind). Thanks for any help
(I already wiped the leaves with white tissues and she doesn't have spidermites, false or otherwise.)