Pileup At The Top

A couple months ago I ran across a cheap, beat-up 1846 Half Dime which looked to be a good pocket piece. Key date in the series too, and I picked it up. Afterwards, I started looking through a few reputable seated websites. Lo and behold, they all had a few 1846 Half Dimes - generally in very high grades, and at very high prices. A month later I ran across a VG-F 1879 half at a bargain price from another dealer. I checked the websites again, and found enough 1879's listed to make up most of a roll. None of them were bargain priced.

What's going on here? Maybe it's a fluke, but I've never seen this abundance of scarce date Seated coinage. On heritage many are previously sold coins being offered for fixed-price sale. Are a lot of old-time coin collectors cashing out their premium pieces right now?