Positive opk at 7dpo!

I took an opk today and it said positive! That's very unusual for me. The first month I started using opk's I used them everyday that month to monitor my cycle and didn't get a positive opk at 7dpo! I took an 88 cent walmart cheapie test with my 3mu and of course it came out negative. I don't have my usual pms symptoms. Just sensitive nipples but no breast pain or craving chocolate etc. Usually by now I experience those things. The only thing I do have is slight muscle pulling by my uterus. Af is due in 7 more days. Given the fact that I had 2 positive opk's today do you think i could actually be pregnant? Has anyone ever experienced this?