Yes, that is typical of the UDM. Before getting the Flex I would only polish with the UDM and after 6-8 hours of polishing at speed 5 or 6, my hand would end up numb, weak and feeling as if I had a really bad case of arthritis (for up to 3 days). Now that I have a Flex, I only use my UDM to apply an
LSP or polish tight spots with a 4'' pad. Oh, I also use it with brush attachments, but never for full polishing jobs anymore.