rusty spots on leaves - please help diagnose (pics)

ok, so i have my g13 diesel fem under a 600 watt mh light. daily temps are around 78 - 80 F and night time temps are around 68 - 70 F. i have noticed some blotchy rust spots on my leaves and it seems to be spreading. some of the edges of the leaves are getting crispy and dying. i can't seem to find anything in the FAQ that looks like this.

this plant was outdoors for awhile, so i'm suspecting some sort of pest, but i have been spraying with neem oil everyday as a safety measure. i also thumped every single leaf on the plant with a peice of paper underneath to try and catch whatever might fall off. nothing did. i have a microscope to identify possible pests, but i haven't found any so far. there was a large wasp and a large ant in my space... i have no idea how they got in... but maybe something hitched a ride on the back of one of them? i have a "hot shot no pest strip" at the ready if this is a bug.

this is super frustrating because otherwise the plant seems really healthy. i'm open to any suggestions basically, i'm sure this could be a nute deficiency that i haven't experienced, so suggest that too if you think that's it. anyway... if anyone can help me out, i would truly appreciate it. i haven't had much experience with pest and diseases (thankfully) so my diagnostic skills are not up to snuff. thanks again.

ps. i know the pics aren't superb, but that's the best i can do. i have an old shitty digital camera that doesn't have a macro setting. i figured something would be better than nothing.

pps. could this be simple nute burn?

looks like the early stages of nute burn to me... fortunately if that's the case it's easily fixed...
I've seen some leaf tips on my plant look that way, but they are the leaves closest to the fan.
Even though I'm constantly told there is no such thing as wind burn... I still hold to it, it makes sense the plant could have trouble keeping that area moist under constant airflow..
If it was a bug other than a mite, I would expect actual chunks of leaf to be missing or holes in the leaves as well. ...and mites are generally easy to find because they stay at the scene of the crime so to speak...

thanks mystik, i hope that you are right. nute burn is a super easy fix. that's true, i never thought about the "staying at the scene of the crime". if i did have spider mites, i would have caught a culprit by now. anyone else?

i wouldnt spray with neem every day,just give it a good watering next time with 1/2 strength and let run out the bottom,then let the plant recover for a week with out spraying,you might want to spray with clean water to wash off residue built up.but ive seen a lot worse on mine with little problem.

That doesn't look like a tremendous problem to me. If that's the best example of the rust spots you could find, I don't think it's a major concern - but based on post counts you've probably had a bit more experience. My current garden has dozens of those, and I've just regarded them as signs that I'm pushing the limit on the combo of nutes, lights and temperature.