Answering a couple of questions...

No, the seamstress didn't touch the lapels. All she did was shorten the length, and replace the ugly buttons for me. I suppose it all depends on what the lapels of the jacket were like originally.

As to figuring out if a jacket is tweed or not, check for labels on the inside. Harris tweed cloth is tweed that is hand woven on the Isle of Harris in Scotland, and all products made from Harris tweed will be labeled as such.

There are tweeds made elsewhere, of course, though they are not as famous as the Harris. But still, there should be a label in the jacket telling you about the cloth.

Aye,
Matt