Extreme humidity can be damaging to a guitar just as extreme dryness can. My [u]guess[/u] is that dryness is more worrisome than moisture but that's a question for the Guitar Tech. Direct your question to the Ask a Guitar Tech sub-forum for an authoritative discussion.

Whatever... it's not the area that the guitar originates from that is the main consideration, it's the environment that the instrument was kept in. Was it high humidity as well, or was it in an air conditioned space? If air conditioned, is there instead a concern for too low humidity?

I would expect a 'guitar shop' in an high-humidity area to be air conditioned like other stores... maybe with more of an eye to guitar-friendly conditions, commonly said to be 45 - 55% humidity, but around the clock air conditioning none the less.

First find out how and where the guitar was kept.