Hmmm even though you had fertile CM and you did have an initial temp jump, the lack of positive OPKs would leave me wondering. Sadly I think the only way you will really get an answer is to continue to wait.
Did you have any "environment" changes this morning that would cause a temp drop? Allergies/stuffy nose that would cause you to sleep with an open mouth resulting in a lower mouth temp? Lack of heat in the bedroom last night? etc?