I can't find the post, but recently I think either Wendell or Leslie posted the CMS regulation about stamped versus electronic signatures & dates. Bottom line, electronic signatures & dates are not prohibited.
It was me, my cover now includes the phrase "this is a computerized signature not a stamp and is acceptable to HCFA. If you will not accept it, please mail me a SASE and original not copy for signature."
I like yours better, I think I will borrow it if you do not mind.