Faint positves due to ovulation

For the past 3 months or so when ive tested at the two week mark or even three week mark and its anywhere near my peak ovulation i get very and i do mean very faint positive test. I take the same brands everytime and the always come back negitive even after checking again days after its still negitive with no evaporation line or anything. Seems like im one getting the faint positives which when i go back to look at to ensure my self (i know there invalid) but the line is also darker. This happend to me today on one of my test. I took a digital and it said no but when i opened it (i know it makes it in valid) it was also a faint positive. I mean like it was there but the camera wont pick it up. HAS ANYONE HAD THIS HAPPEN TO THEM OR NOTICED THIS HAPPENING?