Was your GFR prior to donation 60 ml/min? A creatinine of 0.7 corresponds to a GFR of 94.
Either way, a change in creatinine of 0.7 to 1.4 post-donation is definitely higher than one would expect. And if persistent, it would be worth discussing with your nephrologist. Sometimes, creatinine changes can be transient, or due to medication usage and changes in your hydration. It is also possible that your renal function was not split evenly between two kidneys and if persistent, the creatinine change might reflect you having kept the smaller kidney. However, all of this is speculation without further information as above.