The "wobble" is normal, you can get any one of those contacts to wobble when a tube isnt installed if you manipulate them. The tube pin contacts/solder tabs arent exactly glued into the ceramic socket, they "float" for lack of a better word. It allows for any slightly bent tube pins to still align in the contacts. The wobble really doesnt matter because once the tube is in place, everything is cool as long as the actual tube pin contacts are tight around the pins. The real problem may be a couple loose tube pin contacts themselves (a contact/contacts inside the ceramic not making tight contact around the tube pin/pins). Your fix may be temporary ... by adding solder to keep the tube contact from moving, you may be covering up the real cause of the noise. Atleast for the time being.
If you have any more problems .... you can unplug the amp, remove the tubes, and try tightening the actual tube pin contacts that you think are problematic. Something small enough to squeeze down the hole in the socket and wedge between the ceramic wall and the metal contact, carefully applying pressure to try and close it further so it will make tigher contact on the tube pin. Ive done this before with a vintage amp and still works to this day. You also may want to order a spare socket just to have on hand in case it ultimately needs replacing.
But hey, if it's working now then it aint broke so dont fix it. Besides, I could be totally wrong. It's been know to happen often enough ;D