Acoustics are more susceptible to the bridge pulling up and warping the wood than the necks being strained.
Again though...it's such a small difference in tuning that I can't see it doing anything harmful. However, if you're concerned about problems or intend on leaving the tuning that way for a really extended period of time, you might want to get a lighter string just to play it safe.

I've only had neck or bridge problems twice before.
Once was on an original model of an Ibanez Artist from the 70's, which at the time were considered to be really cheap knockoffs according to my memory.
The neck warped badly in less than a year just tuned to standard tuning.

The second one was a Yamaha 12 string Acoustic (bought at Woolworths of all things). The instructions on the guitar suggested tuning 1/2 step down to avoid warping the bridge because of the extra tension of 12 strings.
Of course I ignored that advice because I wanted to play along in standard tuning and sure enough, in a couple of years the bridge had pulled up and I had to trash the guitar.

What can I say. It's a hard call when it comes to guitars.
It depends on all kinds of things like humidity, temperature differences, types of wood used, quality of workmanship etc etc..

When in doubt though, best play it safe and just spend 2 bucks on a lighter string. :)