Blocking question

I want to knit my mom a shawl out of an alpaca/silk blend yarn. I know it will have to be blocked. My question is, what happens when it needs to be washed? Will it have to be re-blocked?

Yep and maybe even if it gets sprinkled on or terribly terribly humid.

Hmmm, well it seems like kinda of a PITA to give someone a gift that they have to go to such lengths to keep looking nice.