Rather depends what you ate? and how it compares with what you have eaten on other days.
If the only thing that has changed is the removal of the Metform, then that may be the culprit.
On the other hand, if there have been other variables (heat, stress, different activity levels, different foods, different eating times, different portion sizes), then you need to do a lot more testing and comparisons and experiments, before you can draw any firm conclusions.
Hope that helps.