I have change the rule behaviour to avoid having such a smalls nodes.
When using a rule that "Resize by" the nodes, PINV checks for the maximum and minimum value of that feature in the graphic; it then assign those nodes to the smallest size(0.1) and the biggest(4.0), and then, it interpolates all the other nodes for values in between.
Those sizes are scales on terms of area of the node. And that 0.1 was the one causing such a smalls nodes.
I have change the smallest size to be now half the regular node size(0.5) and the biggest to be 5 times the size of a node.
Thanks for the comment.