What might have undermined claims that the colonists did not plan to pursue open rebellion?

The Stamp Act of 1765, imposed taxes over legal transactions such as contracts, wills, and marriage licenses. These were considered to be unfair and rigorous by the citizens of the colonies. They responded violently towards tax collectors by tarring or mocking them in numerous ways. Protest groups such as "Sons of Liberty" emerged during this time.  

All of these reactions could have led the Crown to suspect about an eventual rebellion.

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Explanation:

We can point out to different epsodes that were motives for that, for instance:

The Boston Massacre, Townshend Duties ( the duty on tea remained in force) , The King´s money problem solving with taxes.

All these actions brought people desatisfaction and should be seen as singes of problems.