yes, not to worry. As noted the rubber dries and develops this check cracking over time, because of tire flex as you roll. It's meaningless as long as the tire's fabric plies are intact, as evidenced by even width without lumps or bumps when full.

Minor comment, the tube doesn't stretch the tire. The air inside does, pushing on the tube and tire wall together. The fabric has some give the same way a rope or even a steel cable will stretcha bit when tensioned, which is why the cracks are more visible when the tire id pumped up hard.