Fortunato,

I'm glad you are taking it back to John. You will want to ask him first if this will be a recurring problem. I own a 1957 Martin D-28 (and Rick I don't know if the bass E is sharp). Martin's of this era have weak support under the bridge. Mine, like many, began to bow upwards. I, too, was a medium gauge kinda guy, but after the repair, I've switched to Light or Extra Light on allmost everything I own.

Don't tell anyone, but on my youth I even put heavy gauge strings on my guitar. I guess I just wanted to make some noise.

A little anecdote about the repair. A few months afterward, I was playing my guitar and suddenly heard a loud THUD from the inside. I was pretty worried until I found that the luthier had left one of his tools in, a jack brace that finally came loose. I returned it to the embarassed luthier.

Roger in Baltimore