Positive opk while pregnant?

Kennedy • Married to my soulmate since 7.4.2020!💍💞 We have a 4 year old son, who took a year and a half to conceive! We are expecting baby girl March 11th 2021 after 2 1/2 years of ttc with fertility treatments 💖
I am around 5 weeks pregnant and I took an ovulation test for the hell of it and it came up positive. Any particular reason behind this? And also the green tests are hpts.. Are they getting amy darker?