About 14m30s in, Penny is asking Leonard why he is so bothered about their year's accomplishment list being so empty. As she does so, she keeps looking way off to the left at something off screen.
While Leonard was writing on white board for the x-mas letter, he writes still 'MARTED", meaning to write "married". He actually tried to fix what was to be the 2nd "R", and make it a capital "i" and being under pressure of live taping, it came out as 'MARTED". When the show continues after commercial the spelling had been corrected.