A restaurant served me wine with pieces of cork in the glass. Should I have sent it back?
It depends on your tolerance. I'm the sort who would ask for a spoon to remove the pieces myself.
Small cork particles won't cause harm or yield an off taste, though I'm not a fan of stray bark in my beverage. This is not a case of "corked" wine, by the way, which refers to an odorous taint produced by mould that has combined with chlorine during the cork-production process. Mere cork particles, on the other hand, are purely a physical and aesthetic nuisance.
It's common for dried-out corks to leave behind a few stray remnants when the bottle's opened without sufficient care. They float, so it's easy to scoop them out with a spoon. No big deal.
Most fine restaurants, when politely alerted to the unsightly problem, will replace your glass (assuming you've ordered by the glass). If you've ordered a whole bottle, they may remove the particles (by slowly pouring them into a glass and using the spoon technique) or replace the bottle with a fresh one.