It depends how well the pack actually fits you. The numbers are just a guide and on face value a half inch is well within other adjustments. However a backpack adjusted to the end of its range is likely to be a less ideal fit than the middle of the its range and at the short end may have a tendency to be unbalanced.
If you like the bag, you can fit your stuff in it and it seems to fit then I would suggest loading it up with the things you intend to carry or something of similar weight and bulk and take it for a spin up and down and around, ideally as far as you intend to backpack with it in one shot but 10 mins may be enough to tell you it doesn't work.
That does assume you know how to adjust and wear the backpack to carry it with comfort. If you are unsure I suggest watching a couple of videos. Here is REI's take...
Thanks for reaching out and welcome to the community!
@OldGuyot is spot on in their response, the only thing we wanted to add is that we had a similar conversation a few weeks ago that might also help shed some light on the topic. Feel free to check out the post 'Backpack Sizing - Is There a "Close enough" zone?', by @Dad_Aint_Hip. There is good insight there as well.
Hopefully this helps, thanks!