High OPK 3 DPO...what is going on

Hi everyone, I had a miscarriage on November 5th and D&C on November 13th. My period came back on December 9th. My husband and I decided to start TTC again. My average cycle is 35 days. I track ovulation every month. This cycle, I received a high opk on December 28th and a peak opk on December 29th. It went back to low on Demeber 31st, so I stopped testing. Well, today I tested again just because I felt like it. There was no real reason to. I was bored, expecting to see a low opk, but it came back high. I use the clear blue advanced digital opk.

Any ideas as to what is going on? This has never happened before.