K likes to ride her bike.

We live on a cul de sac and K likes to ride her trike around the 'sac. The trouble comes when she gets to the corner across from our side of the 'sac. She rides down the sidewalk ramp, crosses the street and rides up the other corner. This is a four-way intersection with the other three intersections being mildly busy. Our side of the intersection is not so busy.
Twice today, I've had people stop to comment on this practice. One was a lady who didn't see me and was concerned about such a little girl riding her bike with no mommy or daddy around. I thanked her for her concern and brought K inside for a while.
The second time, I was standing 10-15 feet away from the corner talking to someone when a gentleman in a vehicle stopped to tell me, "I feel uncomfortable with her riding her bike like that." I was completely taken off guard by that one. First of all, I was standing right there, obviously keeping an eye on her. She was not in his way. Second, it wasn't like he'd said, "Letting her ride her bike there isn't a good idea." He said, "I feel uncomfortable...." uhhhhh, sorry? I didn't know what to say. So I smiled, nodded then ignored him. In retrospect, that wasn't the best approach. But still, what was I supposed to say?
When we first moved in, K was riding her bike on the sidewalk toward her daddy when a truck stopped to let Roy know she was riding her bike alone. (Roy wasn't looking at/for her)
Honestly, I appreciate people being concerned and living in a great neighborhood. But I do feel judged, like I'm a less than good parent because I let my three year old ride her trike across the street.
The thing is, K was crossing the entrance to our cul de sac. Not one of these people were entering our cul de sac. They were passing by on the perpendicular street. She was not in their way or on a street they were planning on driving on. I think I'm going to buy a "children playing" sign to put out when we're outside.