They're experts at avoiding confrontations and fights. Move any closer, and the bear will perceive you as a possible threat. This will not be the start of a happy relationship. Just as grizzlies try to avoid confrontations with each other, they generally try to avoid us. Humans rely primarily on sight to detect grizzlies from a safe distance.
Grizzlies depend on their nose but have good vision and hearing, too.
Think about your situation. At that distance, you're not a threat to the bear. There's not much chance it's going to look up, see you, and charge because it feels threatened. Whether you decide to take evasive actions or stay and watch the bear for awhile, you need to ask yourself a few questions. If there's a route that simply allows you to avoid the bear, use it before the bear gets within 100 yards of you.