I say don't worry... but of course I am sure your pediatrician would have better insight.
Sometimes I wish I had a "clinger" but then others times I look at someone who has a little one who is always on them and think "NO WAY would I be able to deal with that." Don't worry :) He sounds like he is just super independent.
I think it is a combo of slightly concerned and also commenting on his independence.
The little girl (2 weeks younger than Phin) that I watch on occasion is the complete opposite and rarely leaves her parents sides, when they are gone she is on me like glue and never plays alone...just interesting to see the differences really.
Oh my gosh... this is funny you brought this up. Leighton does the same thing and my mom was telling me that she thought is was sorta strange (I took her comment with a grain of salt).
Although she will engage in reading books with us or playing on the floor, she won't in public. For instance, library story hour. While the other children her age or about her age are sitting on their mom or dad's lap, my little one is dancing about 5 feet from me and doesn't want me to touch her. She won't let me go near her or touch her and will scream if I do. I just chalk it up to her personality and her independence.
I definitely don't have the shy or publically shy kid. She really does just want to be off on her own and has never run up to us after realizing she can't see us. I am not worried though because I really think it is that she is developing her independence.
Don't feel guilty for not playing with him all the time. He is learning things even without you helping him and some kids just want to be by themselves.
Are you worried about it or just commenting on his behavior? Sometimes it is hard to tell online when you can't engage is full conversation in person :)