Most likely you turned off Constraint Persistance. (looks very similar to Perpendicular Constraint icon and in same general location in 2010.
Or
you might have changed Constraint Options (right click in graphics window while in sketch but with nothing highlighted).
Please mark this response as "Accept as Solution" if it answers your question.
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Autodesk Inventor 2013 Certified Professional
Autodesk AutoCAD 2013 Certified Professional
Certified SolidWorks Professional
Inventor Professional 2013 SP 1.1 Edu 64-bit
GeForce GTX 560M i7-2670QM @ 2.2GHz 8GB RAM
http://home.pct.edu/~jmather/content/DSG322/inventor_surface_tutorials.htm
http://www.autodesk.com/edcommunity
Still waiting for -Draft option on any Rib feature.
