Hey Carbon
It could be a form error and issue with knee position during the squat. If you'd be so kind as to read all the stickies at the top of the forum, you'll find some FAQ's, posting guidelines, and a link to a tendonitis thread that may help.
You'll also find how to become verified so you can post a form check here. You could also post a form check in the Technique sub-forum and see if you can get some insight about your form that may help.
When you say you've been squatting a lot, is that more than the 15 work sets a week during a typical NLP?