Perhaps not. Was it a miracle when Jesus calmed the storm or was it just a coincidence that the wind just stopped blowing? After all after a strong storm the wind can always just inexplicably stop by itself.
So was it a miracle or a coincidence?
There are many explanations for a sickness to heal - medical treatment or the body system rights itself. It is hard to determine a miracle. It is easier if amputated limb will grow by itself.
In the case of sickness, we can say it is a miracle when it is healed without medical intervention, especially when someone prays for it.
A miracle has to go along with the holy life of the canonized saint, which perhaps is more important than a miracle.
God bless.