Might I suggest:
Right click on the layer and select Save As.. then specify a projected coordinate system to do your calculations in.
Convert polygon/line vertices to points instead of Extract Nodes. The first field (ID) is a backslash delimited field with sourceID/part/vertex to allow you to track back.
Delete your duplicates if necessary.
Add coordinates to points on the vertices to allow for easier calculation. I opened the dbf in Excel and used the distance formula:
=SQRT(( G3-G2)*(G3-G2) + (H3-H2)*(H3-H2))
Which is simple Pythagorean maths.
Expanded to new polygons:
Which puts in 'New' when the next vertex isn't the same polygon otherwise the difference. Then using:
=IF(I2 <> 0, IF(I2<2,LEFT(A2,FIND("/",A2)-1),"-1"),-2)
I can find the ID of the polygon that contains short segments, in this case if the distance is 0 (same) then the value is -2, if it's a new polygon or the distance is greater it's -1 and for short segments it's the ID of the polygon.
Then save that to a CSV file (do not save the DBF) and you can reference all the polygons and locations where you have a short segment.
You could achieve similar results using the field calculator in QGIS but I used Excel because it's easier to get to the next row.