age is a factor too.
when i got the Forester (214K miles and 14+ yrs old) and did my initial maintenance on it (timing, plugs, filters, etc..) the radiator hoses looked and felt fine from the outside, but the lower one was so thin in places you could actually see daylight thru it. i was honestly surprised that it wasn't leaking.
needless to say, it, and the upper, got changed immediately, along with that small one you just dealt with, for the simple fact that it was prudent to do so at that time, while the radiator was drained, and things were accessible.
I also changed out pretty much all of the vacuum lines, most of which were hard as a rock.