I haven't seen a doctor about it because it doesn't hurt and because it doesn't cause any loss of function as long as I remember to move my thumbs periodically (and when it does cause an issue, the solution is just to crack them), so treating it would probably do more harm than good. It's more of a curiosity. At this point, it's such a habit to bend my thumbs to crack them that it's rare for them to lock up anymore (it's been probably 15+ years of doing this, so it's basically automatic now).
I don't think it's trigger finger because the sensation is inside the joint rather than the anterior of the thumb, and I have no problem moving it after the crack/pop (I think trigger finger catches every time the lump passes through the sheath). Additionally, from what I can find, trigger finger tends to occur in the metacarpal area, while the affected area on my hands is between the distal and proximal phalanges (the joint right below the thumbnail, not the one near the palm).
I should clarify that I don't have a constant thumbs-up pose. My fingers do relax in a half curl. I mean the distal most joint (nearest the thumb nail) is in a mostly extended pose when relaxed.
